Geological Survey Professional Paper 58 The Guadalupian Fauna

MOLLUSCA.

PELECYPODA.

The Guadalupian pelecypods show considerable diversity. I have discriminated no less than 45 species, representing 23 genera, as follows:

As is usual in the case of Paleozoic material, it has been possible to observe generic characters in extremely few cases, and often more or less valid reason has been recognized for doubting the generic identification. The uncertainty which exists in this particular naturally renders comparisons with other faunas unsatisfactory.

One of the most noticeable features of the Guadalupian Pelecypoda is the differentiation exhibited by the Pectinidæ, which exceeds that of any of the faunas with which comparison has been made.

The Salt Range fauna described by Waagen shows a still more varied pelecypod differentiation than that of the Guadalupian, for he distinguishes 67 species, representing 33 genera. In relatively few cases do the pelecypods of the American and Indian faunas agree even generically, only about 9 out of the 23 Guadalupian or the 33 Salt Range genera being common to both. The genera recorded by Waagen are as follows:

The first 11 genera have, so far as known, no corresponding types in my fauna, though it is possible that Waagen's Cardiomorphan indica and the Guadalupian form doubtfully referred to Clinopistha may prove to be related. The absence of Allerisma from the Guadalupian fauna is a matter of note. The Salt Range shells do not present the most characteristic aspect of the genus (as seen in our Allerisma subcuneatum, etc.), and it may be that some of our Guadalupian types, such as Edmondia? bellula, are congeneric with them.

The presence in both of the widely spread genus Pleurophorus establishes a certain relationship in spite of the fact that the Guadalupian shells are in part too poorly preserved to stand a specific comparison. One can not determine in them the distinctions on which a Waagen differentiates his division identified as Cleidophorus, yet, relying on resemblances to species which have been referred to one type or the other, both have been provisionally recognized. On the strength of their configuration one would be disposed to say that Pleurophorus delawarensis of the Guadalupian corresponded to P. imbricatus and Cleidophorus trapezoidalis; Pleurophorus sp. to Pleurophorus subovalis, and Cleidophorus aff. C. pallasi to C. striantulus, while the Indian P. acutiplicatus is quite without any Guadalupian analogue. The shell which I have described as Protrete texana, though of much smaller size, is somewhat suggestive of Pleurophorus imbricatus, but the resemblance is probably only superficial, as the doubtful Lithodomus appears to possess structures which indicate an entirely different generic relationship.

Schizodus securus can be compared rather with S. rotudatus than with the other Indian species of Schizodus, but is really not very close to any of them. It is probably better compared with the related group of species which Waagen places under Myophorian, though I doubt this relationship for the Guadalupian species, and my material is too scanty to permit me to determine the matter one way or the other. It greatly resembles Myophoria cordissa of Waagen in general outline.

Nuculana subacuta may be compared in a general way with the Guadalupian representative of the genus. The three Guadalupian Nuculas are more or less similar to the Indian shell which Waagen refers to Nucula ventricosa Hall. The other Indian representatives of the genus seem to be of a type at present not known in our fauna.

The single Indian species of Macrodon, with its very coarse ribs, represents a type which is apparently absent from the Guadalupian. Dolabra, which has two Indian representatives, also appears to be wanting, though Edmondia? bellula may possibly prove congeneric. Anything like Septifer squama is likewise alien to our fauna. Lithodomina has not been recognized among the Guadalupian fossils which I have studied, though it is possible that representatives of this genus may have been present among them, the imperfectly known Pleurophorus sp., for instance. While one species belonging to the Guadalupian fauna has been referred to the genus Lithodomus, the form so called is apparently not closely related to L. atavus of the Indian fauna and may turn out to have entirely different generic relations. Nothing resembling Modiola transparens is known in the Guadalupian, but it is not unlikely that Waagen's Mytilus and my Myalina may prove to belong to the same genus and to be not unrelated specifically. Atomodesma or any other form resembling A. indicum is alien to the known Guadalupian fauna.

Of Pseudomonotis Waagen recognizes 6 species, and speaks of its being greatly developed in the Salt Range; but after all the genus appears to be poorly represented, in individuals at least, when compared with the deposits called Permian in the Mississippi Valley. As compared with the Guadalupian, however, the genus may truly be said to be greatly developed, for in that fauna it is as yet entirely unknown.

Nothing like Oxytoma atavum is known from the Guadalupian fauna. Avicula chidruensis appears to be of the same general type as Pteria richardsoni, one at least of the two other Guadalupian species having no correlated form in the Salt Range. Liebea or any closely related type is unknown in the Guadalupian fauna, and Limatulina striaticostata is rather slightly connected with the single Salt Range Lima.

Waagen recognizes 9 species of Aviculipecten and 5 of Pecten in the Salt Range fauna, but the differences on which the two genera have been discriminated it has been impossible to establish among the fragmentary Guadalupian fossils, all of which have been placed with Aviculipecten. In several particulars a correspondence can be traced between the Guadalupian and the Indian forms: Aviculipecten jabiensis suggests A. delawarensis; Pecten prototextorius suggests Aviculipecten sp. b and Aviculipecten sp. c; Pecten squamula is possibly related to Aviculipecten infelix, etc. Shells of the type of Aviculipecten derajatensis and A. pseudoctenostreon, Pecten asiaticus, etc., are not found in the Guadalupian, while Aviculipecten laqueatus, not to mention Acanthopecten and Camptonectes, are not known in the Salt Range. Each of the two faunas contains a single species of Euchodria, and these resemble each other considerably, as must almost necessarily be the case in a genus whose species have so scanty a field of variation. In fine, the faunas of the Productus limestone and of the Guadalupe Mountains have a surprisingly limited common ground.

In his earlier paper on the fauna of Chitichun No. 1 Diener cites only one species of pelecypods, Aviculipecten aff. jabiensis, too small and characterless to be worth much in making comparisons. His later paper contains no mention of this group.

Only slightly more abundant were the forms in the faunas from Kashmir and Spiti studied by the same author. In his first paper on this fauna he cites Modiola? sp. ind., Aviculipecten sp. ind., and Pecten sp. ind., each of which has forms in the Guadalupian more or less comparable, so far as can be determined. In his second paper Diener cites from the lower division only four pelecypod species, but a much more abundant fauna from the upper division. Two of the lower forms are not figured. The Myalina cited as Myalina sp. ind. aff. recurvirostris, and the Aviculipecten cited as Aviculipecten sp. ind. ex aff. A. hiemalis, do not especially resemble Guadalupian species, though they are such as might appear at almost any horizon. From the upper beds Diener cites 9 species, only a very few of which, however, are related to those of the American fauna. Oxytoma laticostatum is non-Guadalupian, Aviculipecten sp. is indifferent, Modiolopsis teplofi is nearest to Cleidophorus aff. C. pallasi, and Solemya biarmica may represent our Pleurophorus delawarensis; but Mytilus sp. ind., Conocardium sp. ind. aff. siculum, Goniomya sp. ind. aff. G. kasanensis, Myophoriopsis? kraffti, and Megalodus sp. are all types unknown in the Guadalupian, except possibly Myophoriopsis? kraffti, which is not without suggestion of relationship to Schizodus securus.

Among the fossils from the Productus shales of Kumaon and Gurhwal the only pelecypod cited is Aviculipecten hiemalis. It is not a species with marked peculiarities, and is suggestive of several Guadalupian types, such as A. guadalupensis and Aviculipecten sp. a.

The same species is cited from Malla Sangcha, along with Leiopteria sp. (not figured) and Lima sp. ind. aff. retifera. The latter is not closely allied to Limatulina striaticostata.

Only three species are cited from the Productus shales of Byans. Leda cf. speluncaria is not unrelated to the Guadalupian Leda, but the Goniomya and the Liebea are alien types.

It is not necessary to particularize the few Carboniferous pelecypods cited from Turkestan by Romanowsky, for they are quite different from the Guadalupian representatives and are in quite different faunal associations; nor will it be necessary to mention especially the single pelecypod described by Salter in his paper on the fossils from Niti Pass, for Aviculipecten hiemalis has already been spoken of in connection with Diener's papers, and is one of those types which are without individuality save as to detail.

Kayser found 11 pelecypod species in his Lo Ping fauna. The 4 species of Aviculipecten, for Avicula sp. is probably to be reckoned in this group, do not offer a very satisfactory basis for comparisons with the Guadalupian fauna. Aviculipecten sublaqueatus is suggestive, in the general style of its sculpture, of the form referred by Kayser to Aviculipecten mccoyi. The other pectinoids are less like Guadalupian types. Nothing resembling Myalina trapezoidalis or Pinna confutsiana is known in our fauna, while the shell identified as Macrodon carbonarius is not closely allied to the Guadalupian Parallelodons. Schizodus wheeleri as identified by Kayser is more like Schizodus securus than the other Chinese representative of the genus, S. lopingensis. Allerisma and Lucina are unknown in the Guadalupian fauna, and the Lo Ping representatives are so imperfect that so far as one can tell from the figures they might belong to quite different genera. The Lucina, for example, suggests the pectinoid genus Streblopteria.

Loczy records a few pelecypod species in the fauna which he described from the vicinity of Kantschoufu. The form cited as ?Lima cf. haueriana is not especially close to Limatulina striaticostata. That cited as ?Aviculipecten cf. exotica appears to be related to Acanthopecten carboniferus of the Pennsylvanian fauna, a species which has been doubtfully recognized in that of the Guadalupe Mountains also. Euchondria tenuilineata as identified by Loczy resembles Aviculipecten? infelix and Euchondria? sp. of the Guadalupe faunas. Gervilleia aff. longa from Kantschoufu is probably congeneric with the Guadalupian species of Pteria, but specifically it is not closely related to them. The Macrodon resembling M. tenuistriatus of Meek is in a general way similar to Parallelodon multistriatus, and the Cardiomorpha is perhaps congeneric with the Guadalupian form resembling Clinopistha radiata var. lævis, but is different in its specific characters.

Among his "Permo-Carboniferous" fossils from the Lantsankiang Valley Loczy cites only one pelecypod, identified as Pseudomonotis? sp. indet. aff. P. deplanata Waagen. It is a very imperfect fragment, but the sculpture at least is of the same general type as in Aviculipecten sublaqueatus.

Loczy also cites a few species of pelecypods from faunas of doubtful geologic age. Such are Posidonomya sp. indet., Allerisma? cf. perelegans, Anoplophora sp. indet. aff. brevis, and Myophoriopsis? sp. The form compared with Allerisma elegans is suggestive of Edmondia? bellula, but the others appear to be unrelated to Guadalupian types.

In his paper on the faunas of Timor and Rotti Rothpletz cites only three species of pelecypods, all referred to the single genus Atomodesma. The only species figured is entirely unlike anything in my fauna.

Roemer cites from Timor two species of Pecten (not figured), one species of Pinna, one of Conocardium, and one of Sanguinolites, in all cases types not known in the Guadalupian.

Roemer's two species of Pecten were recorded by Fliegel as new, under the titles Aviculipecten waageni and A. verbecki. They are of the usual type, which has representatives in many provinces and at many horizons, such as A. guadalupensis and Aviculipecten sp. a of the Guadalupian fauna. A third species of Aviculipecten is also mentioned by this author, who again discusses Roemer's Pinna, together with his Conocardium, as well as another species of the same genus. Roemer's Sanguinolites is probably correctly placed under Allerisma, and another Allerisma is described, but these additions rather increase than diminish the differences which are manifested with the Guadalupian fauna.

The Pelecypoda of New South Wales, recorded in De Koninck's monograph, are of great variety and usually of extraordinary size. Not many of them, however, show any relationship with those of the Guadalupian fauna. With but few exceptions from the lower Carboniferous they were found, so far as I can ascertain, in the "Permo-Carboniferous" series, seldom in both, and while touching somewhat hastily on these I may disregard the others entirely.

Scaldia? lamellifera is probably non-Guadalupian, but it somewhat resembles Edmondia sp. Five Australian "Permo-Carboniferous" species are referred to Sanguinolites, most of them entirely dissimilar to anything known in the Guadalupian. Clarkia myiformis is non-Guadalupian. The two species of Cardiomorpha have nothing in the Guadalupian which appears to resemble them. Edmondia, with three species, is represented in the Guadalupian series, but for the most part by widely different forms. Cardinia fragilis is unlike anything known from the Guadalupian fauna. Pachydomus has not been recognized in the Guadalupian, and the eight Australian species are entirely unlike anything in that fauna. The same is true of the genus Mæonia, with three species. The three species of Pleurophorus are unlike the Guadalupian Pleurophorus. Conocardium (one species) is not known in the Guadalupian, nor Tellinomya (one species), nor Mytilus (two species).

The "Permo-Carboniferous" Aviculipectens of New South Wales comprise about 11 species, some of which, at all events, belong to Etheridge's genus Deltopecten. It could hardly be otherwise than that many of these pectinoid shells should be of the same general type in both faunas. Aside from a few forms which appear to be in poor condition and whose position among the pectinoids appears to be rather questionable, the most striking feature of the Australian representatives of the group is their large size. Perhaps the most noteworthy departure from the usual is found in A. cingendus, which is unlike anything in the Guadalupian. On the other hand, A. laqueatus, A. sublaqueatus, not to mention Acanthopecten, Pernipecten, and Camptonectes, have no kindred types in the "Permo-Carboniferous" of New South Wales.

Aphania, with two Australian species, is entirely non-Guadalupian, so far as known. Of the two species of Pterinea, P. macroptera, subsequently made the type of the genus Merismopteria, is non-Guadalupian, and P. lata only rather remotely resembles the Guadalupian Pterias. Avicula sublunulata somewhat suggests Avicula sp., but A. decipiens and A. intumescens are quite unlike any Guadalupian species, so far as known.

Although not properly mentioned here, the "Permo-Carboniferous" of New South Wales includes several species of Conularia, a genus unknown in the Guadalupian.

Considered as a whole, the "Permo-Carboniferous" pelecypods of New South Wales manifest surprisingly little relationship with those of the Guadalupian fauna. Not only are the genera largely different, but when cited under the same name the species appear to be unrelated. Even in point of size the two faunas are at opposite extremes, the Australian forms being of almost unprecedented largeness and the Guadalupian unusually small.

Etheridge discusses a large pelecypod fauna in his account of the "Permo-Carboniferous" fossils of Queensland and New Guinea, comprising 34 species, distributed as follows:

The single undetermined species of Entolium in a general way resembles Pernipecten obliquus of the Guadalupian. Etheridge's Euchondria is not figured, nor are three of the five species of Aviculipecten. All of the latter appear to have been of the usual type, more or less related to A. guadalupensis and Aviculipecten sp. a.

When I described the genus Limipecten a year or two ago I had not come upon Etheridge's description of Deltopecten, which seems generally to have been overlooked, at least in the works which I have consulted. It appears from Etheridge's description that Deltopecten and Limipecten were designed for the same pectinoid type, and the latter, accordingly, must, so far as is now known, give place to the name proposed by Etheridge. I still regard this as a good genus, contingent on Aviculipecten having the structures which have been ascribed to it. The longitudinal cartilage furrows of the hinge area which Etheridge mentions I would regard merely as accidental irregularities of growth. The hinge structures are not shown on Dana's specimens of Pecten illawarensis, the genotype of Deltopecten, but they are well exhibited on P. leniusculus, having all the characteristics of my Limipecten. It is expected that many other species now referred to Aviculipecten will prove to belong to Deltopecten. D. illawarensis is also one of the ordinary ribbed pectinoids which are found in most upper Paleozoic faunas. It appears to have a few large ribs and therefore to be more like A. delawarensis than A. guadalupensis. Pterinopecten devisii, on the other hand, is not like any of the Guadalupian species.

Merismopteria macroptera and the two species doubtfully referred to Mytilops have, so far as known, no Guadalupian equivalents.

Modiomorpha? daintreei and Modiomorpha mytiliformis contain suggestions of the Guadalupian forms referred to Pleurophorus delawarensis and Cleidophorus sp. aff. C. pallasi De Verneuil, but they may be really quite unrelated. Parallelodon costellatus is probably allied to Parallelodon multistriatus. The undetermined Nucula seems not to be closely related to the Guadalupian Nuculas, but Nuculana sp. is comparable to Leda sp., and Solenomya sp. to the Guadalupian Solenomya.

Pleurophorus randsi probably has no corresponding Guadalupian form. Astartella? rhomboidea is somewhat similar to A. nasuta, but Cypricardella jackii, Astartila cytherca, Eurydesma cordatum, E. sacculus, Conocardium australe, Chaenomya? etheridgei, C.? carinata, C.? acuta, C.? bowenensis, Edmondia? obovata, Sanguinolites concentricus, Pachydomus globosus, Mæonia carinata, and Mæonia recta have no corresponding forms in the Guadalupian fauna. In general, while a number of resemblances among the pelecypods can be pointed out, I doubt whether these indicate any real relationship between the two faunas.

Pelecypods are an important factor in the Russian faunas and dominate the later ones especially, almost to the exclusion of other types; but even in the Moskovian they are fairly well represented, if one may judge by Trautschold's description of that fauna.

Allerisma regulare, which closely resembles our A. subcuneatum or terminale, is unlike anything in the Guadalupian fauna, the absence from which of this familiar and common Pennsylvanian type is one of its peculiarities. Apparently the forms identified as Sanguinolites undatus and S. tetraedrus are also non-Guadalupian. Anatina? attenuata, A.? deltoidea, Conocardium uralicum, and Area argo resemble none of the Guadalupian species yet known. Modiola teplofi can be compared with Pleurophorus delawarensis, but Pinna flexicostata again is a non-Guadalupian type.

That the three Pectens cited by Trautschold should have corresponding types in the Guadalupian is not to be wondered at. The one with unequal ribs and squamose concentric lamellæ (Pecten segregatus) is suggestive of Aviculipecten sublaqueatus. The costate type (P. plicatus) is comparable in a general way with Aviculipecten guadalupensis and Aviculipecten sp. a. The smooth form (Pecten ellipticus) suggests Aviculipecten? infelix and Euchondria? sp. Trautschold's Avicula evanescens appears to be a little pectinoid of the general type of Pecten plicatus of the same fauna.

In the Gschelian a pelecypod fauna in the aggregate large and varied seems to be present. The chief genera which I have found cited are Pecten, Aviculipecten, Lima, Streblopteria, Entolium, Pseudomonotis, Placunopsis, Pseudoplacunopsis, Avicula, Myalina, Pteria, Bakewellia, Pinna, Schizodus, Myophoria, Allerisma, Edmondia, Pleurophorus, Cypricardinia?, Lithodomus, Macrodon, Astarte, and Conocardium. Generically, at least, this list represents a fauna in a general way very similar to that of the Guadalupian, although some groups are found in each which are absent from the other. I have not found it practicable to compare the two faunas in point of their specific differentiation, because in most of the works consulted the pelecypods have been only listed. Stuckenberg, however, describes a fauna in which upward of 40 species are cited and which is perhaps representative of the horizon generally. The pectinoids, including Pecten and Aviculipecten, are rather unusually developed, comprising altogether 14 species. In the main they are pretty well connected with the Guadalupian representatives of Aviculipecten, Streblopteria, and Euchondria, though some types in each are peculiar, and in especial there is nothing among Stuckenberg's forms to compare with the Guadalupian species placed under Camptonectes. The three species of Lima are of a different type from Limatulina striaticostata. There is nothing in the Guadalupian to suggest the three Gschelian species of Avicula, which are probably not congeneric with our Pterias. This relation, however, may exist between the latter and Stuckenberg's Pterinea aviculiformis, which resembles the form from the Delaware Mountain formation called merely Pteria sp. Bakewellia antiqua is not figured, but presumably it resembles the Guadalupian shell doubtfully referred to Bakewellia and cited as Bakewellia? sp. The two species of Pseudomonotis and the two species of Modiola probably have no Guadalupian analogues, though Pseudomonotis cf. tesselati somewhat suggests Aviculipecten sublaqueatus, and Modiola gigantea resembles Cleidophorus sp. cf. C. pallasi; and I am not certain that Myalina lamellosa is very closely allied to M. permiana? or M. squamosa? of the Guadalupian fauna. Macrodon kungurensis seems to be related to Parallelodon multistriatus, but the six other Gschelian Macrodons probably have no corresponding forms. Allerisma regularis and Allerisma sp. belong to types not found in the Guadalupe Mountains. Conocardium cf. hibernicum and the two Gschelian species of Cardiomorpha are probably without Guadalupian equivalents, while the Guadalupian form nearest to Solen sp. is Solenomya sp., found in the black limestone at the base of the Guadalupian section.

Stuckenberg describes in the Artinsk a series of forms almost equally extensive. He discriminates 8 species of Pecten and Aviculipecten, most of which belong to groups that are represented in the Guadalupian also. Aviculipecten kungurensis of the one fauna and A. laqueatus of the other appear to belong to types which are not possessed in common. The two species of Lima are probably closely related to Plagiostoma deltoideum, but the two Artinskian Aviculas are quite distinct from the Guadalupian Pterias, even if they are congeneric with them. Much more closely allied to the latter, in general appearance at least, are Stuckenberg's Bakewellias, especially the one which he describes as B. artiensis. Even this, however, is not closely related in its specific characters, and if they really belong to Bakewellia their only representative in the Guadalupian is probably Bakewellia? sp., which is most closely similar, so far as one may infer, to the unfigured species identified as Bakewellia antiqua. Liebea hausmanni and the two species of Pseudomonotis are non-Guadalupian. Modiolopsis pallasi is presumably related to Cleidophorus aff. C. pallasi. Of the Macrodons, of which three species are cited, I will speak particularly only of Macrodon? cf. parvulus, which alone is figured. The illustration represents a form having an expression considerably different from that typical of the genus, and apparently the Artinskian species belongs to at least a different group from the Guadalupian Parallelodons.

Stuckenberg cites four species of Nucula, two of which are not figured. N. artiensis seems to belong to a different series from the Guadalupian species, but the others are more nearly related. Leda speluncaria, however, differs considerably from the imperfectly known Guadalupian Leda. Stuckenberg's three species of Cardiomorpha are represented by very imperfect material. I have referred no Guadalupian species to this genus, yet, as previously suggested, the form cited under Clinopistha may really belong there, in which case it would more nearly resemble C. silvæ than either of the other types figured by Stuckenberg. His Schizodus sp. is not much like S. securus of the present report, and the Guadalupian shell most resembling Cardinia artiensis and C. plana (but more particularly the former) is that which I have placed under Clinopistha, without any very important evidence for so doing.

From the Kungurstufe Stuckenberg also cites a considerable pelecypod fauna, comprising 22 species. Of the pectinoids, both Pecten and Aviculipecten are represented by one species, the two forms in question apparently being more or less closely allied to Guadalupian types (e. g., Aviculipecten infelix and A. sublaqueatus). Lima kazanensis is much less nearly allied to Limatulina striaticostata than is the other Russian Lima, Plagiostoma permianum, to P. deltoideum. Bakewellia has not been certainly recognized in the Guadalupian fauna, but the single putative species is probably more closely related to the B. antiqua, which Stuckenberg cites, than to the other species of Bakewellia. Pterineopsis, of which Stuckenberg cites one species, is non-Guadalupian. He recognized three species of Modiolopsis and one of Modiola. The corresponding Guadalupian shells are probably those which I have placed under Pleurophorus and Cleidophorus. Modiolopsis teplowi is very suggestive of Pleurophorus delawarensis, and Modiolopsis pallasi is probably equally near Cleidophorus sp. aff. C. pallasi, but M. globosa is different from any known Guadalupian species. Stuckenberg cites four species of Macrodon, but figures only two of them. Macrodon sp. appears to be closely related to Parallelodon multistriatus, but M. cf. striatilamellosus is alien to the American fauna.

The form identified as Nucula trivialis is not unlike one or another of the Guadalupian Nuculas, but Leda speluncaria, Schizodus rossicus, S. truncatus, and S. obscurus are all unlike the Guadalupian species of Leda and Schizodus. The genus Allerisma is not known in the Guadalupian fauna, and while the two Russian shells referred to it are far removed from the typical expression they also appear to have no corresponding types among the Guadalupian fossils.

Krotow has described an extensive pelecypod fauna from the Artinsk, one which comprises in fact no less than 79 species. Unfortunately for my purpose, most of Krotow's identifications are unfigured. Many of the species, however, have already been considered. Under Lima are included two species, L. permiana, which is of course closely allied to Plagiostoma deltoideum, and Lima artiensis, which has no known Guadalupian ally. Pecten receives 13 species, only two of which are figured. Neither of the latter recalls any of the Guadalupian pectinoids. Aviculipecten and Streblopteria are employed by Krotow as subgenera. The latter is cited with but one species and appears to be a non-Guadalupian type. To Avicula are referred nine species, mostly unidentified and all except one unfigured. That one, cited under Pseudomonotis as a subgenus, is unlike any Guadalupian form. Krotow places five species under Bakewellia, three of them unidentified and none of them figured. B. antiqua presumably resembles Bakewellia? sp. of the fauna under discussion, and the others most likely have the configuration at least of some of the Guadalupian Pterias. Aucella is represented by one species, now known as Liebea hausmanni. This type is unrepresented in the Guadalupian. The same is probably true of the two species of Posidonomya which Krotow cites without figures. As in the Guadalupian, the Myalinas seem to be imperfectly represented. Krotow cites only one unfigured species. Pinna, a genus which has not been found in the Guadalupian fauna, is represented in Krotow's Artinskian fauna by one species. Arca, of which Krotow uses Macrodon as a subgenus, comprises nine species, unfigured save in two instances. Parallelodon may be presumed to be the Guadalupian equivalent of these forms. Of the figured species Arca substriata somewhat suggests Parallelodon sp., but A. substriata var. geinitziana has no corresponding form in the Guadalupian. Krotow places four species under Nucula. N. ufimskiana, the only one figured is quite unlike any Guadalupian form. Leda receives two species without any figures. In Schizodus five species are placed. They are not figured, but at least the representation of the genus is much more extensive than in the Guadalupian. Unio castor, the single representative of the genus, is not figured, but presumably it has no Guadalupian representatives. Cardinia has four unfigured species. Solemya embraces two unfigured species more or less related, it may be supposed, to the Guadalupian Solenomyas. Cleidophorus pallasi, which alone represents Cleidophorus, probably is closely related to the Guadalupian shell called Cleidophorus sp. aff. C. pallasi. Astarte is the recipient of two species. A. vallisneriana, the only one figured, is not closely related to Astartella nasuta. Lucina, with two species, seems to be a type which is not found in the Guadalupe Mountains. To Cypricardia are referred two species. Cypricardia is not known in the Guadalupian, and the only species figured is not like any member of that fauna. Goniomya, with one species, is non-Guadalupian. Cardiomorpha has five species, none of which is figured. Probably the nearest related Guadalupian form would prove to be that which has been provisionally referred to Clinopistha. Edmondia includes but two species, neither of which is figured. Sanguinolites has two species and appears to be a type as yet unknown in the Guadalupe Mountains.

So little of Krotow's material is placed in an available form that it is difficult to estimate the real character of the fauna or to compare it with the Guadalupian. The resemblances impress me as being for the most part superficial or general without necessarily implying any intimate relationship.

Among the works consulted which deal with the Russian faunas several others treat of the Artinsk, but only to the extent of listing the species. Although some other genera and a good many additional species might have been obtained from these sources, it seemed best not to give consideration to data presented in this way.

The Permian fauna of Russia appears to be distinguished by its large and varied pelecypod representation, though this is to some extent an appearance relative to some of the other groups, such as the Brachiopoda. Tschernyschew cites 18 species in his paper on the Permian of the government of Kostroma. Two are referred to Allerisma and although they do not represent the most typical form of the genus they probably are not to be correlated with anything in the Guadalupian. Edmondia murchisoniana is of the same general type as E. bellula though distinctly different. Astarte permocarbonica closely resembles Astartella nasuta, but may not be closely related to it. Probably Pleurophorus costatus and Pleurophorus? simplus are less closely allied to Pleurophorus delawarensis than is Solemya biarmica. Leda speluncaria in a general way is comparable to the undetermined Leda from the Guadalupian, and Macrodon kinganus is possibly the Permian representative of Parallelodon politus. Modiolopsis pallasi and Modiola simplicissima are to be compared with Cleidophorus sp. aff. C. pallasi, the former much more than the latter. Bakewellia cerathophaga belongs to a genus which I have only doubtfully recognized in the Guadalupian fauna. Its shape suggests Pteria sp. perhaps more than Bakewellia? sp. Tschernyschew cites one species of Aviculipecten sand three of Pecten, all of which appear to be more or less closely related to Guadalupian types. Pseudomonotis speluncaria is also among the species cited by Tschemyschew, but the genus Pseudomonotis is not known in the Guadalupian fauna.

Much more abundant and varied is the lamellibranch fauna cited by Netschajew from the eastern part of European Russia, which includes over 100 species. Ostrea matercula and Prospondylus liebeanus are entirely unlike anything known from the Guadalupian. Lima retiferiformis and L. kasanensis are somewhat similar to Limatulina walcottianus, and L. permiana is closely related to Plagiostoma deltoideum. Five species are referred to Pecten and six to Aviculipecten. Practically all of these can be compared with one or another of the Guadalupian Aviculipectens except possibly Pecten sericeus. Netschajew discriminates six species of Pseudomonotis, none of which, so far as known, have any Guadalupian representatives. The form described as P. laticostata, however, is almost surely an Oxytoma, while that called P. elegantula looks more like a brachiopod than a pelecypod. The genus Liebea is not known to occur in the Guadalupian fauna. Netschajew cites two species and if they have any related form there, which is rather unlikely, it must be looked for with Myalina. Bakewellia accommodates six of Netschajew's species, which at least simulate the forms referred by me to Pteria. Bakewellia antiqua is suggestive of the Guadalupian type cited as Bakewellia? sp. Several greatly resemble the form from the Delaware Mountain formation which I have called Pteria sp., and also Pteria guadalupensis from the Capitan formation; but one, Bakewellia sulcata, is more like Pteria richardsoni. In a general way the Permian Modiolas (one species) are suggestive of the Guadalupian shells which I have referred to Pleurophorus and Cleidophorus. Modiolopsis teplovi and M. pallasi show the greatest resemblance and Modiolopsis globosus the least. Two Macrodons form a feature of the fauna, identified as M. striatus and M. kinganus, but neither of them is very closely allied to Guadalupian species of Parallelodon, as one appears to be not quite smooth and the other to have pretty coarse ribs. The two Nuculas do not differ materially from the Guadalupian representatives of the genus. Leda kasanensis, rather than L. speluncaria, resembles the imperfectly known Guadalupian Leda. To Palæomutela Netschajew refers no less than 21 species. This type, like several others occurring in the Russian Permian, forms a peculiar group of shells not represented in the Guadalupian. Oligodon, which includes but three of Netschajew's species, is another of these. Dolabra? mackrothi seems to have no Guadalupian equivalent, and none of the three species of Schizodus appears to be at all related to S. securus. Another type alien, so far as known, to the Guadalupian fauna is Naiadites, to which Netschajew refers 18 of his Permian species. Still another of these peculiar shells is Anthracosia, though in this case the genus includes only a single species. Netschajew refers three species to Solenomya, only one of which (S. normalis) indicates much connection with the single Guadalupian species. Pleurophorus simplus is hardly a close relative of P. delawarensis; which, as already remarked, more nearly resembles the Russian Modiolopsis. Astarte permocarbonica and A. wallisneriana are probably represented in the Guadalupian by Astartella nasuta, which is much more nearly allied to the former than to the latter. The two Russian species of Cardiomorpha appear to have no corresponding Guadalupian types. Three species are referred by Netschajew to Edmondia. Edmondia aff. striata rather strongly suggests E.? bellula, but the two others seem to have no related Guadalupian species. Solenopsis parvulus is probably without a Guadalupian ally, though possibly related to Solenomya sp. Goniomya is an entirely non-Guadalupian type, so far as known, and so is Crassiconcha, of which one Permian species is described. Attention has already been called to the absence of Allerisma in the Guadalupian fauna, and the four Permian species cited by Netschajew are without representatives there.

Golowkinsky also describes a Permian fauna from Russia wherein 15 species are discriminated, most of which have also been cited in the works already discussed. Solemya biarmica, Panopæa lunulata, and Osteodesma kutorgana are non-Guadalupian types. The two species of Schizodus are rather unlike S. securus. Nucula beyrichi and Arca kingiana are related, but not closely, to Guadalupian species of Nucula and Parallelodon. A great variety of forms are referred by Golowkinsky to Cleidophorus pallasi, one or two of which are suggestive of Pleurophorus delawarensis and others naturally of Cleidophorus sp. aff. C. pallasi of the Guadalupian. Modiola sp. probably has no Guadalupian analogue. Aucella hausmanni is now recognized as belonging to the genus Liebea and is without any corresponding form in the Guadalupian fauna. The three species of Gervillia comprise the Permian Bakewellias and suggest the type which I have cited as Pteria. Two of them, G. ceratophagus and G. antiqua, more nearly resemble Pteria guadalupensis and Pteria sp. or Bakewellia? sp., respectively, while Gervillia suicata can be compared with Pteria richardsoni. The species cited as Avicula speluncaria is generally regarded as a Pseudomonotis a genus which has no known representatives in the Guadalupian. The shell identified as Pecten sericeus is so imperfect that it is impossible to compare it satisfactorily with the Guadalupian pectinoids.

It will hardly be necessary to consider in detail the Permian pelecypods described in the reports of Keyserling (Petschora-Land) and of Murchison, De Verneuil, and Keyserling, most of which have been cited in the works already discussed, but there must not be passed over without brief notice another reference to a group of forms which seems to be entirely unrepresented in the Guadalupian, but which constitutes an important element in the Permian fauna of Russia. I refer to the Anthracosiidæ and Amalitzky's monograph on the Russian Permian forms. This work discusses 13 species of Carbonicola, 6 species of Anthracosa, 27 species of Palæomutela, 3 species of Oligodon, and 12 species of Naiadites. These genera, with the 61 species included under them, have no equivalents, so far as known, in the American fauna.

Even aside from this extensive and peculiar group of forms, however, the Permian pelecypods of Russia seem to me to present as a whole no very close analogies with those of the Guadalupian fauna. Perhaps an almost equal degree of resemblance is shown by any of the preceding Carboniferous faunas of the same section.

The fauna described by Abich from Djoulfa, in Armenia, has thus far furnished but one species of pelecypod. Abich cited it as Pecten aff. tortilis Semen., but Arthaber has recently referred it to Pseudomonotis. It is doubtful if the Guadalupian fauna has any closely related form.

From Balia Maaden, in Asia Minor, Enderle has cited 4 species of pelecypods, namely, Aviculipecten? sp., Schizodus sp., Pachydomus? sp., and Edmondia bittneri. Only the Schizodus and the Edmondia have been figured. The former belongs to quite a different type from Schizodus securus, and the other is equally different from Edmondia? bellula or Edmondia sp.; in fact, it rather suggests so remotely related a species as Myoconcha costulata.

The Sicilian fauna from Palermo described by Gemmellaro comprises an extensive and varied suite of pelecypods. Forty-eight species are described, referred to the following genera

Gemmellaro's three species of Edmondia are of the general type of the Guadalupian form cited merely as Edmondia sp. He has nothing to compare with Edmondia? bellula. Sanguinolites shumardii is, so far as known, entirely alien to the fauna discovered by the geologist whose name it bears, and the genus Conocardium is also non-Guadalupian. I have not identified the genus Allerisma in the Guadalupian fauna, and while Gemmellaro's two species do not belong to the most characteristic section of the genus, neither appears to have a Guadalupian ally. I have identified the genus Cleidophorus among my fossils, but the single species recognized appears to belong to an entirely different group from Gemmellaro's. The genus Geinitzia is unknown in our fauna, but a certain resemblance, perhaps only superficial, appears to exist between the Geinitzias (not to mention Gemmellaro's peculiar species of Cleidophorus, which considerably resemble his Geinitzias) and the imperfectly known Guadalupian shells which I have referred to Myoconcha. Of Gemmellaro's four species of Macrodon, M. whitei and M. latisinuatus are quite different from the Guadalupian forms. His figures of M. comptus suggest the imperfectly known Parallelodon sp., and M. multilamellatus, with its almost invisible striæ, appears to be related on the one hand to Parallelodon politus, which is quite smooth, and on the other to P. multistriatus, which is finely lirate. Gemmellaro's two species of Arca resemble nothing yet found in the Guadalupian. I have not referred any Guadalupian species to Pseudomonotis, a genus which finds four representatives in the Sicilian fauna, but one of Gemmellaro's species (Pseudomonotis fimbriata) is suggestive of a form which it seemed best to me to identify with Aviculipecten. I refer to A. sublaqueatus; and A. laqueatus itself may possibly belong in the comparison. The single Guadalupian type doubtfully referred to Bakewellia is quite distinct from B. elegans, which suggests no relationship, either, with the Guadalupian Pterias. Liebea? mediterrana and Avicula josephinæ are non-Guadalupian.

It has not seemed to me appropriate to refer any Guadalupian shells to Leiopteria, but Gemmellaro's species have similar if not related forms in the Guadalupian fauna. The Guadalupian forms in question have been referred to the genus Pteria, but only the unidentified one from the Delaware Mountain sandstone much resembles the Sicilian Leiopterias, which to a limited extent have the configuration of Bakewellia? sp., which was also obtained from the Delaware Mountain. Rutotia thyrrena is not figured. The genus Pinna has as yet failed to appear among the Guadalupian faunas.

The Sicilian Aviculipectens are not very suggestive of those of the Guadalupe Mountains. A. sicanus, A. bertrandi, A. densistriatus, and A. nitidus probably have no closely related forms. A. acanthicus looks like our Pennsylvanian Acanthopecten carboniferus, which I have identified in the Guadalupian fauna also, and A. janus has points of resemblance with the same species as well as with A. sublaqueatus.

Gemmellaro's Streblopteria pusilla and S. antinorii resemble the Guadalupian species identified as Euchondria? sp. and Aviculipecten infelix, but may have no real relationship.

The two Sicilian species of Limatulina have little to do with the single Guadalupian species, and I am doubtful as to their belonging to that genus. L. consanguinea especially suggests to me one of the Pectinidæ, rather than the Limidæ. Among the Guadalupian pectinoids Aviculipecten sp. a most resembles it. Pecten politus has no closely allied Guadalupian species, so far as known. Lima connectens may be compared with Plagiostoma deltoideum, but probably is not closely related specifically. Lima subretifera, however, is far removed from the Guadalupian Limatulina striaticostata, while Anomia prisca is quite unlike any type known to occur in the Guadalupian.

Although the Sicilian fauna and that from the Guadalupe Mountains seem to have a considerable number of common genera they evince but little actual relationship. In many cases though the genus is the same the species belong to altogether different groups, while there is after all considerable difference in the generic types. On the part of the Guadalupian mention may be made of Solenomya, Clinopistha, Nucula, Leda, Yoldia, Pteria (in part), Myalina Schizodus, Camptonectes (which has no parallel in any of the other faunas considered), Lithodomus?, Astartella, and others, depending on how accurately the generic titles indicate the exact relations of forms whose generic characters can often be only imperfectly deciphered. Some of these identifications of Guadalupian forms are decidedly open to question, but the absence from the Sicilian fauna of such characteristic Carboniferous genera as Nucula, Leda, Myalina, Schizodus, and Astartella is certainly worth remarking. On the other hand, this fauna contains a number of types which are alien to the Guadalupian, some more, some less, among which may be mentioned Sanguinolites, Conocardium, Allerisma, Geinitzia, Arca, Pseudomonotis, Liebea, Rutotia, Pinna, and Anomia.

I have been led to infer that Schellwien has never described this class of organisms as it occurs in the fauna of the Carnic Alps, but in a recent paper by Gortani from the same region a number of species belonging to this group have been cited. To the genera Pecten and Aviculipecten are attributed eight species, some of which are not figured. In view of this fact and of the rather unsatisfactory character of the illustrations it is difficult to make comparisons, but apparently there is little of a marked character in the Alpine pectinoids to distinguish them from the Guadalupian Aviculipectens. One of the species cited is Aviculipecten carboniferus, a characteristic species of our Pennsylvanian, which seems to have an identical or kindred form in the Delaware Mountain formation of the Guadalupian also. Aviculipecten incarojanus is a peculiar form for the genus, and rather suggests the type which I have placed with Pteria, resembling more or less Pteria sp. or Pteria guadalupensis. The form referred to Pecten (Streblopteria) sericeus De Verneuil is not figured, but presumably resembles one of several smooth pectinoid species in the Guadalupian fauna. Pecten (Entolium) cf. aviculatus, also not figured, is presumably related to Pernipecten obliquus. Lima retiferiformis appears to be rather widely different from the Guadalupian representative of the Limatulinas. Liebea hausmanni and Myophoriopsis? carbonifera are non-Guadalupian, so far as known, and Schizodus pinguis though not figured is considerably different from S. securus.

So poor are the figures of the two species of Astarte recognized in the report of Gortani that their characters are as much concealed as depicted, but they may be presumed to be more or less closely allied to Astartella nasuta. Conocardium, to which Gortani refers one species, is not known in the Guadalupian.

A pelecypod fauna of considerable extent is described by Geinitz from the Dyas of Germany. Allerisma is represented by Allerisma elegans King, but Geinitz's figures represent possibly two species. The type is not known in the Guadalupian. Two, possibly three, species appear to be represented by Geinitz's figures of Panopæa lunulata. One of them is suggestive of Edmondia. bellula, but no Guadalupian shells like the other forms are yet known. Panopæa mackrothi is suggestive of an Edmondia, of the same general type as Edmondia sp. of the Guadalupian. Tellina dunelmensis is not figured, but apparently it resembles Edmondia? bellula, superficially at least. Solenomya biarmica is related, though not closely, to the Guadalupian representative of the genus, but the type of S. normalis appears to be absent in our fauna. Several species of Unio and Anodonta may also probably be called non-Guadalupian. Lucina minuta is not figured, but is likewise an alien type. Astarte vallisneriana and A.? tunstallensis are presumably more or less related to Astartella nasuta, but the three species of Schizodus show wide differences from S. securus. Arca kingiana seems to correspond to Parallelodon politus, but Arca striata, while of the same general type as Parallelodon multistriatus, is considerably different. The two Nuculas cited by Geinitz, but more N. beyrichi than N. wymmensis, are not markedly different from the Guadalupian Nuculas, and Leda speluncaria exhibits a similar general resemblance to Leda sp. of our fauna. Edmondia elongata is hardly a nearly related form to E.? bellula, resembling rather Edmondia sp. More than a single species seems to be figured under each of the titles Clidophorus pallasi, C. hollebeni, and Pleurophorus costatus, and most of the types are not found in the Guadalupian. They resemble Pleurophorus delawarensis to only a limited degree, but C. pallasi especially is similar to Cleidophorus sp. aff. C. pallasi. One of Geinitz's figures of Clidophorus paliasi somewhat recalls Myoconcha costulata. Aucella hausmanni, now known to belong to the genus Liebea, is an unknown type in the Guadalupian. Avicula speluncaria, which is now generally cited as a Pseudomonotis, is also non-Guadalupian, and nothing resembling A. kasanensis has been obtained from that fauna. A. lorata is imperfectly known, as is also A. keyserlingi, though Keyserling's figures certainly suggest a form like our Acanthopecten carboniferus, which though described from the Pennsylvanian appears to occur in the Guadalupian fauna also. A. pinniformis, however, is a non-Guadalupian type.

Geinitz refers four species to Gervillia. Some at least of these belong to the genus Bakewellia, to which some of the Guadalupian Pterias which they suggest in general expression appear not to belong. G. ceratophagus and G. sedgwickiana are the species which especially resemble the Guadalupian Pterias, particularly Pteria sp. from the Delaware Mountain formation, and Pteria guadalupensis. Gervillia antiqua is more like the Guadalupian form described farther on as Bakewellia? sp. G. murchisoni is unlike any Guadalupian species, so far as I am aware, but suggests one from the Pennsylvanian which White described as Anthracoptera polita and which I subsequently thought might be a Monopteria. The Pectens appear to be much less multifariously represented, both in genera and species, in the Dyas. Geinitz cites three species of Pecten and one of Lima. Only one of the Pectens is a costate type, the others being smooth. P. kokscharofi resembles several Guadalupian species. P. pusillus and P. sericeus, by their lack of sculpture, also resemble several Guadalupian species, such as Aviculipecten infelix and Euchondria? sp., but whether there is any real relationship I am somewhat in doubt. The Guadalupian equivalent of Lima permiana is Plagiostoma deltoideum.

A very similar fauna is that of the Permian of England, from which King described a considerable number of pelecypods. The first two cited are Pecten pusillus and Lima permiana, which have just been mentioned. All the costate types of Pecten or Aviculipecten seem to be absent. Pseudomonotis, however, is represented by P. speluncaria (under which are included a great variety of forms and possibly several species), P. radiata, and P. garforthensis. None of these types is known to occur in the Guadalupian. Mytilus squamosus, however, is represented in that fauna by a form so closely related that I think them to be not improbably the same species, but M. septifer seems to have no corresponding type, unless possibly Myoconcha sp. proves to be such. Edmondia murchisoniana somewhat recalls E.? bellula. King's species of Bakewellia, of which there are five, very strongly suggest the Guadalupian shells which I have referred to Pteria, although I have been unable recognize the characteristic structures of Bakewellia in my specimens. B. ceratophaga resembles to a greater or less degree Pteria sp. and P. guadalupensis, and B. bicarinata is similarly like Pteria richardsoni. B. antiqua rather strongly resembles the Guadalupian shell described as Bakewellia? sp., and in fact it was because of this resemblance that the reference to Bakewellia was made. B. tumida is less like any known Guadalupian species, while on the other hand no English Permian form seems comparable to Pteria squamifera.

King uses Bissoarca for the genus that is here called Parallelodon. B. striata and B. tumida are very much more coarsely ribbed than Parallelodon multistriatus, while B. kingiana, instead of being smooth, as described by De Verneuil, and therefore closely related to Parallelodon politus, is stated by King to be marked with incipient ribs. Nucula tateiana which is not figured, can hardly be considered different from the Guadalupian Nuculas, but Leda vinti certainly differs widely from the imperfect Leda known from that fauna. Of the two species of Janeia, J. phillipsiana may perhaps be compared with Solenomya sp., but J. biarmica is less distinctly related.

King's Cardiomorpha modioliformis suggests no Guadalupian species so much as that which I have described as Cleidophorus sp. aff. C. pallasi, or to a less degree Myoconcha costulata. Pleurophorus costatus is represented generically in the Guadalupian fauna but not by a species of the same group. None of King's four Permian species of Schizodus possesses a close specific relationship with the singular S. securus. The two Astartes presumably are congeneric with Astartella nasuta, and Astarte tunstallensis resembles the Guadalupian species considerably in shape though not in sculpture. Allerisma elegans is a type, so far as known, which is non-Guadalupian. The Permian shell which King cites as Psammobia? subpapyracea has a general superficial resemblance to Edmondia? bellula, but it is doubtful whether any real relationship exists.

From the south point of Spitzbergen Toula cites four species of Aviculipecten. They show no marked departures from Guadalupian types. Aviculipecten wilczeki, which he described from the Hornsund, seems to be of the same general character as A. laqueatus. From Axel Island he cites two species of Gervillia, that which is figured resembling the Guadalupian species which I have called Bakewellia? sp. Aviculipecten draschei from the same locality is of a type which is common everywhere and at many horizons in the Carboniferous, so far as is now apparent.

Lundgren cited a considerable pelecypod fauna from the Permian of Spitzbergen, but unfortunately many of his species are unfigured. The fauna includes two species of Pecten and six of Aviculipecten, one of Avicula, two of Pseudomonotis, one of Gervillia, two of Bakewellia, two of Leda, one of Myalina, and one of Allerisma. Such of the Pectens and Aviculipectens as are figured have more or less nearly related types in the Guadalupe Mountains. Avicula? sp. is not figured, nor is one of the species of Pseudomonotis. The other impresses me as much more apt to be an Aviculipecten than a Pseudomonotis, but if correctly placed it would, so far as known, be without any corresponding Guadalupian form. Gereillia? sp. is unidentified and unfigured. Bakewellia antiqua and Bakewellia cf. sedgwickiana, also not figured, are related to the Guadalupian Pterias and to Bakewellia? sp. if to anything in that fauna. Leda sp. and Leda? sp. are not figured. Myalina degeeri is unlike the Myalinas of the Guadalupian, and Allerisma? sp., though not figured, is also probably non-Guadalupian.

From the Barents Islands, near Nova Zembla, Toula cites a number of pelecypods, two species of Avicula, three of Aviculipecten, one of Mytilus, one of Leda, one of Schizodus, one of Allerisma, one of Pleurophorus, one of Sanguinolaria, one of Edmondia?, and one of Astarte, but as they have little to do with the Guadalupian pelecypods and are associated with a different fauna, I will not comment on them in detail.

From Igidi, in the West Sahara, in association with a fauna which I take to be considerably older than the Guadalupian, Stache cites a few species of pelecypods, as Pecten cf. P. mactatus De Koninck, Pecten sp., ? Gervillia sp., and ?Anthracosia sp. The two latter are not figured, and only the first mentioned is suitable for consideration. The form in question resembles Aviculipecten laqueatus in its sculpture, but the shape is different.

Certainly our knowledge of South American pelecypods of the Carboniferous is very imperfect. I have found citations of only two species, which D'Orbigny described from Bolivia as Pecten paradezii and Trigonia antiqua, the latter probably being closely related generically and specifically to our American Astartella vera. The Pecten is of the same general type as some of the Guadalupian Aviculi pectens, but the Astartella is widely different from Astartella nasuta.

The typical Pennsylvanian fauna as it stands in Weller's valuable bibliography contains slightly over 200 species of pelecypods, representing 48 different genera. A considerable number of these, it is true, have never been figured, and if they were known to-day would doubtless be found to belong to other genera than those under which they were first described and are now cited, and in some cases to be synonyms for other species. On the other hand, there have not been included in this enumeration a few species and genera which have been introduced since the bibliography was published.

The Guadalupian fauna contains but few generic types which do not occur in the Pennsylvanian, although the specific representation is so profoundly different. In fact, only four instances can be named—Lithodomus, Plagiostoma, Camptonectes?, and Myoconcha—in which it has been deemed necessary to refer the Guadalupian types entirely to non-Pennsylvanian genera. Yet it is rather likely that the difference is somewhat greater than this, for it should be remembered that the real generic characters have seldom been observed in Guadalupian forms, most of them having been referred, on the strength of configuration and general expression alone, to the genera with which I was familiar and to which they seemed in these particulars most closely related. As the genera familiar to me were naturally such as occur in our Pennsylvanian and Mississippian rocks, the generic list necessarily simulates that of our normal Pennsylvanian fauna, yet in some cases, where the specific type shows exceptional differences, it seems likely that if the generic characters could be known the forms would prove to belong to distinct if related genera. Schizodus securus is a case in point, and I rather expect that at some day data which are not now at hand will show that the genus is not Schizodus, but possibly Myophoria or some other.

The number of Pennsylvanian genera which are not found in the Guadalupian, to estimate which is a simple matter, amounts to something like 28, or over 50 per cent, but this fails to convey a true idea of the relations of the two faunas. Some of the genera, as, for instance, Arca, would almost certainly disappear from the enumeration if the Pennsylvanian forms representing them were at all known, while certain types are of such rare occurrence, even in the Pennsylvanian, that they can hardly be regarded as characteristic genera whose absence from the Guadalupian has any significance. It would not be unprofitable, however, to consider some of the fairly abundant and characteristic Pennsylvanian types whose absence from the Guadalupian may be regarded somewhat insignificant.

The first of these, alphabetically at least, is Allerisma. A. terminale, or A. subcuneatum, is a common and very characteristic species of our Pennsylvanian, and the entire absence of this type from the Guadalupian is certainly noteworthy. Neither the typical division of the genera nor those other species, some of which I have withdrawn into the newly erected genus Pleurophorella, have so far as known any representatives there. Shells belonging to the genera Aviculipinna and Pinna are not uncommon in local collections from the Pennsylvanian, and the absence of this type also is worthy of note. Bakewellia has not been certainly recognized in the Guadalupian, while shells referred to this genus are sometimes abundant in the later Carboniferous deposits of Kansas and Nebraska. Yet, just as I have been unable to detect the characterizing structures of Bakewellia in the Guadalupian Pterias, I have been unable to detect them in the common Pennsylvanian Bakewellias also, so that it is not improbable that Pteria (at least in part) of the one fauna corresponds to Bakewellia of the other. Cardiomorpha and Clinopistha are very abundant at certain horizons of the Pennsylvanian, frequently occurring in association. One or the other type, I am not entirely sure which, though I have identified it as Clinopistha, is represented in the lowest strata of the Guadalupian, but the other is not known there. Conocardium is not abundant in the Pennsylvanian, but its absence from the Guadalupian should not be overlooked in this place. Monopteria is another Pennsylvanian type which appears to be absent, and while it is not very common as a rule, it may be said to be one of the characteristic genera. Pseudomonotis, with which can almost certainly be included some of the types recorded as Monotis, is rather abundant at some of the higher horizons of the Carboniferous in the Mississippi Valley, and its absence in the Guadalupian, so far as known, is rather remarkable. Chaenomya and Sedgwickia, closely related genera to Allerisma, though less abundant in the Pennsylvanian, show, with that genus, the fact of nonappearance in the Guadalupian.

Although in the main the generic representation of the Guadalupian and Pennsylvanian faunas appears to be nearly the same, but very few species occur in common, while in a few cases the specific types are very different. The single Guadalupian species of Astartella is not sufficiently different from the Pennsylvanian ones to cause much remark, and the same is true of the Pennsylvanian Aviculas, which with the Bakewellias may provisionally be regarded as equivalent to the Guadalupian Pterias. The type seems to be much more abundant in the Guadalupian, however, being, so far as my experience goes, for the most part rather rare in the Pennsylvanian. Among the pectinoids the representation in the main presents few striking differences, save that they are rather more abundant and highly differentiated in the Guadalupian. Euchondria, Pernipecten, Aviculipecten, Acanthopecten, and Limatulina occur in both faunas. The absence of Pseudomonotis from the Guadalupian has already been commented on, while the introduction of the singular type referred to Camptonectes? is one of this fanna's individual features. The specific representation of these genera, while different in the main, is too similar to evoke comment, except perhaps in the case of Limatulina striaticostata, which is widely different from the Pennsylvanian Limatulina retifera. The smooth type of Lima (Plagiostoma), represented in the Guadalupian by P. deltoideum, is, so far as known, absent from the Pennsylvanian. This type is a feature of the Permian faunas of Russia, Germany, and England. Clinopistha has closely allied types in both faunas, so far as can be made out, but the Guadalupian shell may not belong to the genus at all. Cypricardinia calls for no comment. Edmondia is apt to be pretty common in the Pennsylvanian, the prevailing type there being represented in the Guadalupian by a single imperfect specimen. No marked differences are shown by the genus Parallelodon, but Myalina again is a significant factor, as shells belonging to this genus are often common and of large size in the Pennsylvanian, but in the Guadalupian they are rare and small. The common Pennsylvanian type M. subquadrata is not represented in the other fauna. Nucula and Nuculana offer no striking differences, nor does Pleurophorus to any great extent, though the genus appears to be more plentiful and varied in the Pennsylvanian rocks, presenting certain types which are absent from the Guadalupian. Schizodus contains as marked elements of difference as almost any genus common to the two faunas. Schizodus is abundant and well differentiated in the Pennsylvanian, but in the Guadalupian only one rare species has come to hand, and it is so different from the Pennsylvanian types that I have a suspicion that it may belong to a different genus. Solenomya has furnished many more species to the Pennsylvanian fauna, but it is far from a common Pennsylvanian type, and the single imperfectly known Guadalupian species does not show any marked peculiarities. The same is true, though to a less degree, of the genus Yoldia.

In brief, for two faunas so closely situated geographically the Guadalupian fauna and that of the Pennsylvanian, together with the so-called Permian of the Mississippi Valley, show unusually marked differences, which must connote corresponding ones of geologic age, of environment, or of both. Possibly their proximity in geographic position finds expression in the generic similarity, while the strong specific unlikeness may be interpreted as due to chronologic succession. Although the Guadalupian pelecypods, as just said, unquestionably show important differences from the Pennsylvanian forms, their relationship to that fauna appears to me to be as close, perhaps even closer than to any other of the faunas which have come under observation.

Family SOLENOMYIDÆ Gray.

Genus SOLENOMYA Lamarck.

SOLENOMYA? sp.

This type is represented by two very fragmentary specimens from the black limestone at the base of the Guadalupe section. So far as can be ascertained, the shape and other characters indicate a relationship to the Solenomyas of the Pennsylvanian, but particularly to the form which Herrick described as S. subradiata. The shape is rather more symmetrically rounded behind than in the related species S. radiata, and the radiating lines are more indistinct. In one specimen, in fact, they can hardly be observed at all, and in the other they are also very faint though unmistakable. They are rather closely arranged and more numerous than in Herrick's species S. subradiata, so that if it prove to be really a member of this genus the form under consideration is very probably a new species.

Horizon and locality.—Basal black limestone, Guadalupe Point, Guadalupe Mountains, Texas (station 2967).

Genus CLINOPISTHA Meek and Worthen.

CLINOPISTHA? cf. C. RADIATA var. LÆVIS M. and W.

This type is represented by a specimen from the lowest horizon of the Guadalupe section. Its generic characters are entirely unknown, and even the shape has been more or less obscured by crushing. So far as can be determined, however it is extremely suggestive of Clinopistha radiata, especially the variety which Meek and Worthen described as lævis. Radiating sculpture is entirely lacking and the thin shell is covered only by fine concentric striæ and occasionally others of greater breadth.

Horizon and locality.—Basal black limestone, Guadalupe Point, Guadalupe Mountains, Texas (station 2967).

Family GRAMMYSIIDÆ Fischer.

Genus EDMONDIA De Koninck.

EDMONDIA? BELLULA n. sp.

Pl. IX, figs. 22 to 22b.

Shell small, transverse, elliptical. Posterior end somewhat higher than the anterior. Beak of moderate size, subcentral, but distinctly anterior to the median line.

Surface nearly smooth; marked by a few rather faint but large concentric ridges.

This species most nearly resembles Edmondia glabra Meek, but besides being very much smaller it is somewhat differently shaped, and has smaller and less projecting umbones. It is perhaps the form cited by Shumard from this locality as Edmondia suborbiculata. This species Shumard gives to Swallow, but Swallow's species is named Edmondia semiorbiculata, and it is evident that suborbiculata was a clerical error on the part of Shumard, who also gave the page reference incorrectly (20 instead of 190). It would hardly be necessary to refer to these matters were it not for the fact that Weller's catalogue, though for the most part accurate, cites suborbiculata as Shumard's species, a circumstance which tends to give currency to a somewhat obvious error.

Edmondia semiorbiculata is certainly a similar species to that in hand, though I doubt if it be really the same. It is, however, impossible to arrive at a certain conclusion until both species are better known, especially that of Swallow, which has never been figured. The latter is evidently related to Edmondia glabra, and being near the same horizon may prove to be the same thing.

Horizon and locality.—Middle of Capitan formation, Capitan Peak (station 2926); Delaware Mountain formation, Guadalupe Point (station 2931?), Guadalupe Mountains, Texas.

EDMONDIA sp.

From the Delaware Mountain formation there is in our collection a single imperfect specimen of an Edmondia, which seems to belong to a species related to E. aspinwallensis, E. nebraskensis, E. ovata, and E. subtruncata. The shape is somewhat transverse and elliptical, the umbo inflated and projecting, and the surface marked by rather prominent, somewhat regular concentric ridges. The present material is inadequate to ascertain the specific relations.

Horizon and locality.—Delaware Mountain formation, Guadalupe Point, Guadalupe Mountains, Texas (station 2931).

Family NUCULIDÆ Adams.

Genus NUCULA Lamarck.

NUCULA sp. a.

Pl. XXIV, fig. 22.

This form is represented by three rather imperfect specimens from the lowest beds of the Guadalupe section. The size is rather small, the largest example having a width of only about 7 mm. The proportional height varies somewhat in different specimens, but is usually two-thirds to three-fourths the width. The beak is small and not very prominent. The posterior outline below the umbones projects rather strongly and is well rounded. The lower outline is gently convex, the anterior end strongly rounded, and the upper margin, more or less rectilinear, slopes strongly downward. The surface is marked by concentric striæ which are moderately fine, faint, and regular.

This little form resembles that which Meek found at Nebraska City, and which he hesitatingly identified as Nucula beyrichi. It is somewhat larger and perhaps a little more elevated in proportion to the width.

Horizon and locality.—Basal black limestone, Guadalupe Point, Guadalupe Mountains, Texas (station 2967).

NUCULA sp. b.

Pl. XXIII, fig. 8.

The specimen on which this species is established is an internal mold from the Delaware Mountain formation. It is somewhat small and transverse, the width being 6-1/2 mm. and the height 4 mm. The beak is rather large and projecting, situated about one-fourth the width from the posterior margin. The upper and lower borders contract behind, the anterior and posterior extremities being strongly rounded.

The anterior teeth are rather numerous; about 14 can be counted. Sculpture unknown.

In addition to the specimens from the Delaware Mountain sandstone on which the foregoing description is based another example from the underlying black limestone has been assigned here. It is in a measure intermediate between the present species and Nucula sp. a, with which it occurs in association, being not quite as transverse as the one and distinctly more transverse than the other.

Horizon and locality.—Delaware Mountain formation, Guadalupe Point (station 2931); basal black limestone, Guadalupe Point (station 2967?), Guadalupe Mountains, Texas.

NUCULA sp. c.

Pl. XXIX, fig. 11.

This form is represented by a single somewhat imperfect specimen from the southern Delawares. The shape is subquadrate; the beak, situated almost terminally, is small and not much projecting. The superior margin is gently convex; the posterior margin is nearly straight and directed almost perpendicularly to it. The lower margin is strongly bowed, and joins the anterior and posterior outlines in rather abrupt turns.

The surface is unknown, but probably was nearly smooth.

The type specimen is a left valve, and shows on the inside about 9 anterior and 6 posterior teeth.

This form is nearest that distinguished as Nucula sp. a, but is clearly a different species.

Horizon and locality.—Delaware Mountain formation, southern Delaware Mountains, Texas (station 2969).

Family LEDIDÆ Adams.

Genus LEDA Schumacher.

LEDA sp.

In the black limestone at the base of the Guadalupe section has been found a single specimen of a species of Leda. It is an internal mold, and represents a small shell, which is very transverse, elongate, and tapering. The shape is suggestive rather of the variety attenuata than of the form commonly identified as Leda bellistriata, but it is even more attenuate. The length of the only specimen obtained is 12 mm., of which 8 mm. is anterior to the beak. The greatest height—that at the umbo—is 5.5 mm.

Horizon and locality.—Basal black limestone, Guadalupe Point, Guadalupe Mountains, Texas (station 2920).

Genus YOLDIA Möller.

YOLDIA sp.

A single specimen represents this species, the source of which was in the black limestone at the base of the Guadalupe section. It is unfortunately too imperfect for illustration or description, but appears to be generically related to Yoldia subscitula and to resemble it in specific characters also. As compared with Meek's figure of Y. subscitula in his work on the paleontology of eastern Nebraska, the Guadalupian shell appears to be somewhat more broadly rounded behind and to have the anterior extension more tapering and less distinctly truncated. A shallow sinus indents the shell, beginning at the umbones and slightly sloping forward.

Horizon and locality.—Basal black limestone, Guadalupe Point, Guadalupe Mountains, Texas (station 2967).

Family PARALLELODONTIDÆ Dall.

Genus PARALLELODON Meek.

This generic name has been but little adopted by American writers, the shells which belong to it almost universally passing under Macrodon Lycett. When Lycett introduced the term for the molluscan type in 1845, however, it had already been preoccupied by Macrodon Muller, 1842, a genus of fishes. Meek called attention to this fact in 1866,a and suggested Parallelodon as a substitute. Parallelodon was taken up by De Koninck, but by few other authors, though recently it has again been revived by Hind.b

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aProc. Chicago Acad. Sci., 1866, p. 17.

b British Carb. Lam., Pal. Soc., 1896-1900, p. 125.

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Macrodon is based on a type from the English Lias, and according to Hind shows certain subordinate differences of dentition from the Carboniferous Parallelodons, of which P. delicatus of the American Pennsylvanian must probably be taken as the type. Both because the term Macrodon was preoccupied, because Macrodon was based on a Mesozoic and Parallelodon on a Paleozoic type, and because they show certain differences in dentition, though these may be small, it seems to me highly advisable, especially in the case of Paleozoic species, to use the term Parallelodon.

The Guadalupian Parallelodons are three in number, and each species must probably be regarded as belonging to a distinct group. The two forms which can with reasonable certainty be included in the genus are quite distinct from the Pennsylvanian species, without, however, exhibiting any marked departures from the types prevalent in that period.

PARALLELODON MULTISTRIATUS n. sp.

Pl. XXXI, figs. 13 to 14a.

Shell of medium size. Configuration as in other members of the genus. Surface marked by a few lamellose, concentric lines and by numerous extremely fine radiating liræ. Of the latter about ten occur in the space of 2 mm. over the mesial third of the surface, but they increase in coarseness both posteriorly and anteriorly.

The types of this species are silicified shells from the Glass Mountains, both of them being unfortunately incomplete in the posterior portion. The configuration in this genus is so constant and the part that remains in the present specimens is so characteristic that I feel that the validity of the species is but little affected by the circumstance of their incompleteness. The configuration so far as known, for the reason given above and because it is well shown by the illustration, has not been described in detail. The generic characters and general aspect are those of Macrodon.

A single example from the Delaware Mountain formation has been identified with this species. In this case also only the anterior half of the shell is preserved. In the white limestone of the Capitan formation still another specimen has come to hand which is even more imperfect, and therefore has been referred here with some doubt. The surface is well shown, and presents about the anterior third to view. The striation of the anterior end of the portion preserved is relatively rather coarse, while that of the posterior end is scarcely to be seen without the aid of a glass. This specimen is large, and may not be specifically the same as those from the Delaware Mountain formation or as those from the Glass Mountains.

Parallelodon multistriatus is distinguished from P. tenuistriatus by the fine striæ which completely cover the surface. On the type specimen of P. tenuistriatus the upper posterior portion has a few moderately coarse ribs, the rest of the shell being without radiating sculpture, except for faint striæ near the lower margin, especially toward the middle and toward the anterior end. Parallelodon obsoletus is very close to P. tenuistriatus, and is distinguished by the same characters from the Guadalupian form. Very faint traces of fine radiating striæ can be seen near the lower margin of the type specimens of P. obsoletus also, and I doubt if it will be practicable to retain both species.

Horizon and locality.—Middle of Capitan formation, Capitan Peak (station 2926?); Delaware Mountain formation, Guadalupe Point (station 2931), Guadalupe Mountains, Texas. Delaware Mountain formation, Comanche Canyon, Glass Mountains, Texas (station 3763).

PARALLELODON POLITUS n. sp.

Pl. IX, fig. 25.

Shell of medium size, transverse, strongly arched. Anterior end pointed, projecting. Posterior end obliquely truncate. Lower margin convex, gently curving upward at the posterior extremity, strongly curved at the anterior.

Surface without radiating striæ, but showing usually concentric ones of varying prominence and regularity.

The upper Carboniferous Parallelodons do not exhibit much diversity in shape, the distinguishing character being chiefly that of surface ornamentation. In this respect the present species differs from others of the genus, since it is entirely without traces of radiating striæ. An approach to this character is seen in Parallelodon obsoletus, in which the obvious striæ are confined to the area near the hinge line behind the umbones. Even in this species, however, very faint traces of ribs appear on other portions of the shell, though the absence of them was supposed by Meek to serve as a distinguishing character from P. tenuistriatus.

The type specimen of the species was derived from the Capitan formation. In the Delaware Mountain formation also some specimens were found in which no radiating striæ have been discovered, and it is supposed that these examples belong to the same species. The Delawarian specimens attain a considerable size, the largest having a transverse diameter of not less than 40 mm. These examples are preserved as partial internal molds, and it can not be asserted positively that the surface was entirely smooth, as in the specimens from the white limestone.

Horizon and locality.—Middle of Capitan formation, Capitan Peak (station 2926); Delaware Mountain formation, Guadalupe Point (station 2931), Guadalupe Mountains, Texas. Delaware Mountain formation, southern Delaware Mountains, Texas (station 2969?).

PARALLELODON? sp.

Pl. XXXI, fig. 15.

The general character of this form is shown by the figure. It is supposed to represent a species of Parallelodon, though the specimen is too imperfect to allow this fact to be made evident, while some features are a little unfavorable to such an identification.

The posterior wing is depressed and rather sharply defined from the elevated umbonal ridge, a condition which carries a certain suggestion of the Pteriidæ. The rather large ribs are coarsely crenulated, which gives them a nodulose appearance. This tendency is, however, not uncommon to Parallelodon, in which the ribs often have an interrupted look, especially where, as frequently happens, they become faint over the median third of the shell.

The nearest related species to the present one among our known Pennsylvanian forms is evidently Parrallelodon obsoletus, from which it appears to be distinguished by the strength of the umbonal ridge and the very marked crenulation of the ribs.

Horizon and locality.—Delaware Mountain formation, Comanche Canyon, Glass Mountains, Texas (station 3763).

Family PERNIDÆ Zittel.

Genus BAKEWELLIA King.

BAKEWELLIA? sp.

Under this title are included a few imperfect specimens from the Delaware Mountain formation, which in a general way resemble the associated shells referred to Pteria richardsoni, but appear to differ from them (for of some of the differences I can not be quite sure) in being slightly less oblique, in having a smaller, less distinct and rounded anterior lobe, and in lacking a posterior alation. Instead, the posterior outline is nearly straight, meeting the cardinal line at an obtuse but distinct angle.

The hinge characters are best shown in a right valve preserved as an internal mold. There appears to have been a long linear posterior furrow, defined by projections both above and below. Of cardinal teeth there appear to have been two, with sockets possibly for three on the opposing valve. The anterior sockets were two in number, the upper one short and parallel to the hinge, the lower longer and strongly inclined downward. They inclose between them a prominent tooth, and connect behind with two of the cardinal sockets. In the left valve the only structure preserved is a posterior furrow similar to that in the other valve. It seems probable, therefore, that this structure indicates the position of a resilium rather than standing for a posterior tooth and socket.

Aside from being somewhat less oblique, this form much resembles Bakewellia antiqua as figured by King.a It has a similar rounded anterior end and is likewise not extended into a mucronate alation behind. The dentition also resembles that figured by King.b On the other hand, the condition of my material is not such as to permit me to determine whether any ligamental pits were present or not.

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aKing, W., Monograph of the Permian fossils of England, Palæontographical Society, 1850, pl. 14, figs. 28, 29.

bIdem, fig. 34.

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From present knowledge it seems hardly probable that this form belongs with the Pterias of the Guadalupian, though it resembles them superficially, and it is even regarded as not impossible that it is related to Myoconcha costulata var. delawarensis, Pleurophorus delawarensis, or Cleidophorus aff. pallasi, diverse as they are. Whether the relationship is that of belonging to the same genus, of being a variety of the same species, or of being young, abnormal, or imperfectly preserved individuals can not now be told.

While this material probably differs even generically from the several species of Pteria, it has been difficult to distinguish it from the associated form referred to P. richardsoni, since most of the material is imperfect. It resembles Bakewellia parva in its configuration, but is less oblique and possesses so different an articulus so far as can be made out, that it probably belongs to a different genus.

Horizon and locality.—Delaware Mountain formation, Guadalupe Point, Guadalupe Mountains, Texas (station 2931).

Family PTERIIDÆ Meek.

Genus PTERIA Scopoli.

Shells of this type are unusually plentiful and varied in the Guadalupian fauna if that of the Pennsylvanian be taken as a standard. Four species have been obtained, whereas in an equal amount of Pennsylvanian material it is doubtful if one would have been present. This is not quite true, however, if the so-called Bakewellias of the Pennsylvanian be taken into account since they are sometimes fairly abundant, though presenting but little variety.

In fact the Guadalupian shells which are here included under Pteria superficially resemble very closely some of the European species of Bakewellia, just as some of the smaller examples placed with Pteria sp. much resemble the small, poorly characterized Pennsylvanian Bakewellia parva. In the case of the latter species the best evidence I have been able to obtain indicates that the hinge is constructed differently from that in typical Bakewellia. Hinge structures are hardly to be observed in the Guadalupian shells, but in no case has the typical Bakewellian articulus been made out, and in some it appears to be absent.

On this account I have not felt justified in referring my species to Bakewellia, in spite of their resemblance in some cases to the European Bakewellias and the significance which by reason of their differentiation and abundance they might have in correlating the Guadalupian fauna. It is possible that this significance may yet be shown either by the present forms proving to be Bakewellias or by some of the European ones proving to belong to other genera.

PTERIA GUADALUPENSIS n. sp.

Pl. IX, figs. 20 and 20a.

This species is based on a left valve which has the following characters:

Shell small, very oblique. Anterior auricle small, defined by a shallow depression producing an inflexion in the growth lines and a sinus in the anterior outline. The body of the shell is much prolonged and is strongly convex transversely. It is abruptly and deeply depressed on the upper side of the umbonal ridge to the level of the posterior wing, which is flattened, produced, mucronate, and with a deep emargination below.

The surface is marked by fine, strong, and somewhat irregular concentric lamellæ.

This species most nearly resembles Avicula tonga Geinitz,a from which it does not differ materially in outline. In this regard my specimen does not depart farther from Geinitz's figure of A. longa than does Meek's figure of the same species.a Geinitz, however, describes A. longa as nearly smooth, while the Guadalupian form is marked by rather strong lamellæ.

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aCarb. und Dyas in Nebraska, Dresden, 1866, pl. 2, fig. 15.

aFinal Rept. U. S. Geol. Survey Nebraska, etc., 1872, Pl. IX, fig. 9.

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Horizon and locality.—Top of Capitan formation, Capitan Peak (station 2966); middle of Capitan formation, Capitan Peak (station 2926), Guadalupe Mountains, Texas.

PTERIA SQUAMIFERA n. sp.

Pl. XXXI, figs. 11 and 11a.

This species is founded on a left valve which has the following characters:

Shell small, strongly oblique. Umbonal ridge elevated, subangular, making an angle of 30° with the hinge line. Posterior wing large, flattened. Posterior outline between the umbonal ridge and the mucronate cardinal extremity deeply concave. The termination of the umbonal ridge is sharply rounded, the anterior outline gently curved, and the anterior superior angle rounded. A small groove, sharply defined and angular on its posterior side, limits an otherwise inconspicuous auricle and makes a slight sinus in the anterior outline.

The surface is marked by small convex scalelike projections which have a rather obvious concentric arrangement, being perhaps something in the nature of interrupted concentric laminæ. An obscure radiating arrangement can also be seen. On the posterior wing after becoming transformed into lamellose liræ, with a direction parallel to the outline, they die out almost entirely. They are abruptly revived on the hinge line, however, which is strongly crenulated. The anterior auricle seems to be without ornamentation, except irregular wrinkles.

The peculiar surface ornamentation of this species, in conjunction with the shape, render unnecessary comparisons with other American species.

Horizon and locality.—Delaware Mountain formation, Comanche Canyon, Glass Mountains, Texas (station 3763).

PTERIA RICHARDSONI n. sp.

Pl. XXIX, fig. 14.

Shell small, strongly oblique. Posterior ear depressed, moderately wide, prolonged, pointed, defined in outline by a deep sinus. Umbonal slope subangular, slightly curved, addressed to the cardinal line at an angle of about 45°. Body of the shell narrow, strongly produced backward, limited in front by an angular rib nearly perpendicular to the hinge line, and abruptly raised on the anterior side by reason of a depressed area which it serves partially to define. The depressed area continues anteriorly for nearly half of a quadrant, when there is another abrupt elevation directed at about 45° to the hinge, the remaining portion of the anterior end being well rounded.

Surface where well preserved marked by more or less irregular, closely arranged, squamose concentric liræ.

This form is related to Avicula sulcata Geinitz.b The shape is rather similar but is less flattened below, while Geinitz's species has three costæ in front instead of two.

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bCarb. und Dyas in Nebraska, Dresden, 1866, pl. 2, fig. 16.

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The typical specimens were collected by Mr. Richardson in the limestones of the southern Delawares, but apparently the same species occurs in the Delaware Mountain formation of the Guadalupe section.

The forms so identified occur associated with the large specimens which have been described as Pteria sp., and I am not sure but that some of them are young shells of that species. At first I took them to be representatives of the genus Bakewellia, and, indeed, the question for all the Guadalupian Pterias, whether they should be referred to Pteria or Bakewellia, is in some dubitation, but what little of their structure is known does not agree especially well with Bakewellia.

These small Guadalupian forms range in size to a length along the umbonal ridge of 5 mm. or less. They vary somewhat in different characters, and especially in the degree in which the anterior lobe is defined by an abruptly sunken area. There is a suggestion in this that more than one species is represented, though intergradation is present to some extent, but my material is difficult to deal with owing to its imperfect and fragmentary condition. Some examples resemble our well-known Bakewellia parva.

I venture to record in this connection the observation of structures in Bakewellia parva which render it very doubtful if that species is really a representative of King's genus. Bakewellia is described by King as dimyarian, with a high area and plurality of cartilage pits, and several linear anterior and posterior teeth, like Cucullæa. The area is usually rather low in Bakewellia parva. In several instances I have ascertained the presence of a comparatively large triangular cartilage pit in each valve beneath the beak, but no trace of other similar structures has been seen along the cardinal line. The specimens most favorable for studying these characters were preserved as molds. In this condition on the right valve are to be found a long linear posterior ridge parallel to the hinge line, bounded by furrows, and a similar short one anterior to the umbones. These indicate on the shell itself a long posterior groove bounded by raised ridges, and a short anterior one of the same nature. Correspondingly, in the left valve there appear to have been a strong short linear anterior tooth and a long linear posterior tooth. The muscular equipment consists of a single large, strongly impressed scar similar in position to the anterior scar of Bakewellia. The pallial line traced backward from this becomes fainter until no longer seen, nor does it seem to lead to any posterior scar, the presence or position of which is unascertained. It seems probable, however, that a faint posterior scar really does exist, effecting a muscular arrangement analogous to that of Bakewellia.

Zittel's text-book of paleontology, American edition, gives a definition of Bakewellia which departs in many particulars from that of King. It is assigned to the Pernidæ, and should therefore be monomyarian, with the anterior adductor absent in the adult, with three to four denticulations under the beak, and a serial multivincular ligament. It is evident that B. parva is altogether different from this description. It is nearer the type of structure defined by King as Bakewellia, but I strongly distrust the propriety of leaving it with that genus at all, because it is alivincular instead of multivincular and because the denticulation is somewhat different and more simple. If, as I suspect, in spite of the fact that only one muscle scar has been observed, Bakewellia parva is dimyarian, it can hardly be placed with the Pteriidæ, where it would be natural to refer it.

Horizon and locality.—Delaware Mountain formation, Guadalupe Point, Guadalupe Mountains, Texas (station 2931?). Delaware Mountain formation, southern Delaware Mountains, Texas (station 2969).

PTERIA sp.

Pl. XXIII, fig. 1.

In the yellow sandstone of the Delaware Mountain formation a large aviculoid occurs, which is, however, too imperfectly known to permit its satisfactory discrimination, though probably it is new. The general shape is that of Avicula longa Geinitz, though the size is much greater and the posterior wing larger and possibly less extended (?). The surface ornamentation is not known. The present surface, which is that of a compressed mold, retaining in some degree both internal and external markings, shows only fine concentric striæ, which in some places give evidence of having been rather coarse, rounded, regular, and strong.

Horizon and locality.—Delaware Mountain formation, Guadalupe Point, Guadalupe Mountains, Texas (station 2931).

Family MYALINIDÆ Frech.

Genus MYALINA De Koninck.

This genus, the only Guadalupian representative of the Myalinidae, is poorly represented, both in species and individuals, in our fauna. Two or three specimens of a very small species closely related to M. squamosa of the European Permian, and two large fragmentary examples of the general type of M. permiana of the Pennsylvanian, are all that have been found. In considerable contrast stand the Pennsylvanian and "Permian" of the Mississippi Valley, where the genus is often plentiful and the individuals of robust dimensions.

MYALINA SQUAMOSA Sowerby?.

Pl. XVI, fig. 22; Pl. XXIX, fig. 15.

1829. Mytilus squamosus. Sowerby, Trans. Geol. Soc. London, 2d ser., vol. 3, p. 120. [Permian]: Ferry Bridge, England.

1850. Mytilus squamosus. King, Mon. Perm. Foss. England, Pal. Soc., p. 159, pl. 14, figs. 1-7.

Permian: Ferry Bridge, Hampole, Tunstall Hill, Dalton-la-Dale, Humbleton Quarry, and Silksworth, England.

1859. Myalina squamosa. Shumard, Trans. Acad. Sci. St. Louis, vol. 1, p. 396 (date of volume, 1860).

White [Permian] limestone: Guadalupe Mountains.

This form is found equally in Shumard's dark and in his light limestone, though it seems to be more abundant in the latter. We have six specimens from the Capitan limestone, but they are all very fragmentary, while the single specimen from the dark limestone is more complete, and has therefore been used for illustration. It more nearly resembles certain Mississippian species, so far as its characters are known, than the common "Coal Measures" forms. It might pass for a young example of M. perattenuata, but seems especially near M. squamosa Sowerby as figured by King from the Permian of England. There seems to be no essential difference in shape, though the American species may have had a more nearly smooth surface, lacking perhaps the lamellose striæ which give name to the English one. Of this, however, I can not be certain, lacking English material with which to make comparison and being in some doubt about the normal type and range of variation shown by the American form because of its imperfect preservation. From the wide difference in the associated faunas in each case it seems a little improbable that there should be actual specific identity in this instance.

Two specimens from the southern Delawares have also been referred to this species. One of them has lost its surface characters, but the other, which is represented by fig. 15 of Pl. XXIX, is crossed by strongly projecting concentric lamellæ arranged at regular but ever increasing intervals.

Horizon and locality.—Middle of Capitan formation, Capitan Peak (station 2926); "dark limestone," Pine Spring (station 2930), Guadalupe Mountains, Texas. Delaware Mountain formation, southern Delaware Mountains, Texas (station 2969).

MYALINA PERMIANA Swallow?

1858. Mytilus (Myalina) Permianus. Swallow, Trans. Acad. Sci. St. Louis, vol. 1 (date of volume, 1860) p. 187.

Permian (?): Kansas.

1864. Myalina permiana. Meek and Hayden, Pal. upper Missouri, Smithsonian Cont. Knowl. No. 172, p. 52, pl. 2, figs. 7a-7c.

Permian: Smoky Hill Fork of Kansas River and Cottonwood Creek, Kansas.

?1877. Myalina Permiana. Hall and Whitfield, Rapt. U. S. Geol. Explor. 40th Par., vol. 4, p. 276, pl. 6, fig. 7.

"Permo-Carboniferous:" Foothills southeast of Salt Lake City, Wasatch Range, Utah.

?1881. Myalina permiana. White, Rept. U. S. Geog. Surv. W. 100th Mer., vol. 3, Suppl., Appendix, p. xxv, pl. 3, figs. 1a-1d.

Carboniferous: Coyote Creek, New Mexico.

1891. Myalina permiana. White, Bull. U. S. Geol. Survey No. 77, p. 28, pl. 4, figs. 16-19.

Permian: Godwin Creek and Military Crossing, Baylor County, Tex.; Camp Creek, Archer County, Tex.

From the Delaware Mountain formation two specimens of Myalina have come to hand, but they are in a much crushed and imperfect condition. The larger and more complete specimen closely resembles the shell figured by White as M. permiana and represented by fig. 18 of Pl. IV of his report on the Texas Permian,a but my material is so poor that I can not vouch for the identification. White identifies M. aviculoides, M. perattenuata, and M. permiana in this report, but I am disposed to question whether there was really more than one species in his material; certainly, whether the division made by him is correct. White's fossils are nearer to Meek's interpretation of M. permiana than to either of the other species with which he identifies them, but I am not altogether satisfied of the identity even in this case. My specimen, in having an extremely slight swelling of the outline under the beak, resembles White's examples of M. perattenuata more than Meek's, in which the shell recedes so that its outline seen from above overhangs the actual margin.

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aBull. U. S. Geol. Survey No. 77, 1891.

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Horizon and locality.—Delaware Mountain formation, Guadalupe Point, Guadalupe Mountains, Texas (station 2931).

Family TRIGONIIDÆ Lamarck.

Genus SCHIZODUS King.

This genus, which is rather common at many localities in the upper Carboniferous of the Mississippi Valley, is represented in the Guadalupian by a single specimen, which is, moreover, of a strongly marked character, altogether different from the usual Pennsylvanian types.

SCHIZODUS SECURUS Shumard?

Pl. IX, fig. 24.

1859. Axinus securus. Shumard, Trans. Acad. Sci. St. Louis, vol. 1, p. 397 (date of volume, 1860).

White [Permian] limestone, Guadalupe Mountains.

Shell compressed, length and height nearly equal; anterior margin gently curved, and about one-third shorter than the basal margin, which is gently rounded; posterior extremity rather sharply angulated; posterior slope obtusely subangular. Surface markings unknown.

Resembles A. rotundatus, Brown; but the valves of our species are more flattened, the buccal margin longer and not so strongly arched, and the beak is situated nearer the anterior extremity.

Locality.—White limestone, Guadalupe Mountains.

The foregoing is Shumard's characterization of this species, and it must be confessed to be rather incomplete, in view of the fact that it was not supplemented by figures. In the more recent collections but a single specimen has come to hand which can be said with any probability to represent Axinus securus, and this is, unfortunately, imperfect, owing to which circumstance, in connection with the briefness of the description, it is impossible to verify the identification or to amplify the description. So far, however, as Shumard does define the characters of his species, my specimen is in fairly complete agreement. The most marked feature of this form, whose general character can be seen from the illustration, is the sharpness of the umbonal ridge, the posterior face of which is actually concave toward the beak. This character is found to some extent in most members of the genus, but in none of our American species, so far as I am aware, to the same degree. Shumard appears to refer to this feature as the posterior slope, which he defines as "obtusely subangular," an expression which hardly seems to do justice to the fact, if my specimen belongs to his species.

This species would probably best be assigned to the well-known genus Schizodus.

Horizon and locality.—Middle of Capitan formation, Capitan Peak, Guadalupe Mountains, Texas (station 2926).

Family PECTINIDÆ

The Pectinidæ are unusually well differentiated in the Guadalupian, perhaps not so much so as in the Pennsylvanian as a whole, but more than in most Pennsylvanian faunas of equal extent. The family comprises the genera Camptonectes?, Aviculipecten, Acanthopecten, Euchondria, and Pernipecten, types all of which occur in the Pennsylvanian also, with the very important exception of Camptonectes?. That singular and elegant type is an important element of individuality in the pelecypod fauna of the Guadalupian, whether comparisons are made with the Pennsylvanian or with known Carboniferous faunas of other parts of the world. The other genera whose presence in the Guadalupian is a matter of community with the Pennsylvanian are for the most part doubtfully determined. Acanthopecten is known but as a fragment, Euchondria has not been proved in its generic characters, and Pernipecten has by no means a typical expression. In the case of Aviculipecten, in both faunas there occur a number of forms whose internal structures are unknown and whose generic position with Aviculipecten, as against Pecten, Deltopecten, and possibly other genera, is yet to be demonstrated.

Genus CAMPTONECTES Agassiz?

This title is used for a peculiar group of forms which occurs in abundance in the Capitan formation of the Guadalupian series. Among its distinguishing characteristics the most striking are its forward obliquity, the large anterior and small posterior ear, the lack of definition of the posterior ear, and the surface ornamentation. The latter character proves to be very variable. It seems to consist primarily of nodes or papillæ which are arranged in curved diagonal lines outwardly concave. These nodes, which distinguish the surface of C.? papillatus, appear to have been connected with tubules traversing the shell at a strongly acute angle with the surface, and probably were continued outward into spines, which lay nearly flat along the shell in a radial direction.

With this character is probably connected an observation made on a shell related to those under consideration. In this instance the test was seen to be minutely and abundantly punctate, somewhat as in Terebratula or Eumetria. This is the only example in which punctation was observed, and it is on a much finer scale than the tubules in C.? papillatus; but as will later appear, this group shows wide variations in the scale of its ornamentation. Toward the circumference the rows of nodes tend to pass into continuous liræ, a circumstance which connects this species with C.? sculptilis. There the liræ tend to diverge pinnately from a median line, curving outward as they go. In C.? asperatus the two types of surface are more or less combined, but on a greatly reduced scale and with some modifications. Minute tubulous papillæ cover the surface, but over the peripheral portions tend to form continuous liræ, which, however, are not in two sets with a pinnate arrangement, but in multiple groups and with a zigzag direction. It is probably with an ornamentation of this type that the punctate shell above referred to is most easily to be compared. Another factor which may be of importance is that on internal molds of the right valve the anterior ear shows obscure traces of radiating ribs, which are not seen on the exterior.

These shells in some respects can be appropriately compared with McCoy's genus Streblopteria. The forward prolongation of the shell is a rather striking character of both, and still further agreement can be traced in the fact that the anterior ear is defined and the posterior undefined. On the other hand, the type species of Streblopteria is smooth, while these Guadalupian shells have the peculiar ornamentation above described. Furthermore, typical Streblopteria has a large posterior and a small anterior ear. This is one of the diagnostic characters mentioned by McCoy. Unfortunately, in the case of Streblopteria, as well as in Camptonectes?, no comparison can be made in the matter of internal characters.

Camptonectes seems to agree with the Guadalupian forms in having a large, well-defined anterior ear and small, undefined posterior ear. In some species, at least, it has the same forward prolongation. The characteristic external feature of Camptonectes consists, however, in the radiating liræ which diverge along a median line. This peculiar style of sculpture is repeated in C.? sculptilis, but the singular surface features of the other Guadalupian forms which are manifestly closely related to C.? sculptilis are unknown in Camptonectes proper. The punctate structure, which can hardly prove an erroneous observation, is altogether an anomalous character. Of the two genera considered, the Guadalupian forms appear to present points of closer similarity with Camptonectes. If the observations recorded here are established by further research, it seems certain, however, that they belong to a genus yet undefined.

These anteriorly projecting pectinoids have much in common with certain of the Pteriidæ, which will have to be brought into closer comparison when revision is made. One marked difference found in the Guadalupian shells is that they are rather conspicuously equivalve, while the Pteriidæ have one valve characteristically smaller than the other.

CAMPTONECTES? PAPILLATUS n. sp.

Pl. IX, figs. 3 and 3a.

The type specimen of this species is a left valve, and from it the following description is taken:

Shell small, rather oblique, and inclined forward. Convexity low and broad, hinge line short. Posterior ear probably small and undefined, anterior ear large and defined both by a notch in the outline and by being sharply depressed below the curvature of the body of the shell. The axis is curved, concave toward the anterior side. The surface is marked with papillæ, which increase in size proportionally to the dimensions of the shell. Over the upper half they are small, and the surface appears to be almost smooth. They have a sort of quincunx arrangement such that they tend to form two sets of curved lines intersecting at an acute angle. These lines are concave toward the anterior and posterior sides of the shell. Their curvature is greatest near the margins, especially near the lateral margins. In this region also the linear arrangement is more strongly marked, and tends to develop into connected ribs. The papillæ appear to have been the bases of small spines pointing radially and almost tangential to the surface.

In addition to the type specimen, four other examples have come to hand, all left valves. They are small and more or less imperfect both as to shape and surface ornamentation, and it can not be told with certainty whether they belong here or with C.? sculptilis. The right valve is unknown, though probably among a number of right valves whose surface has been destroyed by exfoliation representatives of this species are found. It is probable that the right valve is the counterpart of the other in surface and configuration.

Horizon and locality.—Middle of Capitan formation, Capitan Peak (station 2926); Delaware Mountain formation, Guadalupe Point (station 2931), Guadalupe Mountains, Texas.

CAMPTONECTES? SCULPTILIS n. sp.

Pl. IX, figs. 4 to 5a.

This species is manifestly related to Camptonectes? papillatus, and differs from it chiefly in having more strongly developed surface ornamentation. This is characteristically shown by the imperfect right valve serving as the original of fig. 4, and consists of two sets of curved liræ apparently developed pinnately along the median line. The liræ are not unlike the rows of pustules which form the surface ornamentation of C.? papillatus, and it will be recalled that in the latter they tend to develop into liræ near the margins of the shell. There can be no doubt, however, that the surface in the two typical examples under consideration is widely different, though it seems likely that intermediates occur. Several other specimens from the same horizon appear to have a surface marked like the imperfect example already mentioned, rather than like C.? papillatus, and they probably belong to the same species. Besides differing in surface ornamentation from C.? papillatus, they are more elongate and have the anterior ear somewhat differently shaped. These are, however, young examples, with somewhat obscured surface characters, and it is not certain that they represent the same species as the large and strikingly sculptured but imperfect specimen.

Horizon and locality.—Middle of Capitan formation, Capitan Peak, Guadalupe Mountains, Texas (station 2926).

CAMPTONECTES? ASPERATUS n. sp.

Pl. IX, figs. 1 to 2.

This species much resembles Camptonectes? papillatus, the chief difference being in the surface ornamentation. The shape appears to be almost identically the same, but as the typical examples are right valves there is a deep notch under the anterior ear. The surface is of the same character as in C.? papillatus, but on a very much finer scale. Apparently two types of surface are found to occur on the same shell, one consisting of intersecting rows of papillæ and the other of intersecting liræ. I am inclined to believe that the two kinds of surface are more or less alternating. The scale is so small in the case of this species that it is difficult to tell whether the lines are continuous or interrupted; and it seems probable that preservation might alter the appearance to some degree. The lines have a more or less zigzag appearance on a portion of the surface.

All of these specimens are right valves, and as they occur in the same beds with C.? papillatus, which is represented by left valves, the presumptive evidence is certainly considerable that they belong together. On the other hand, the surface ornamentation though of the same general character as in C.? papillatus is yet so different in effect that the greater probability seems to favor regarding them as distinct. Furthermore, in C.? sculptilis both valves seem to have the same and not different ornamentation, though this fact, which would be important if proved, can not be insisted on, because some uncertainty exists as to whether all the shells referred to sculptilis really are of the same species.

The fossils representing these species indicate that the two valves are practically equal, and that they have similar if not the same surface ornamentation. They contrast with Aviculipecten, where, as is well known, the right valve is distinctly flatter than the left and is frequently almost without ornamentation.

Horizon and locality.—Middle of Capitan formation, Capitan Peak, Guadalupe Mountains, Texas (station 2926).

Genus AVICULIPECTEN McCoy.

This genus is well represented in the Guadalupian fauna, nine varieties having been discriminated. In no instance have the generic characters been observed, so that I am unable to say definitely that any one species actually belongs to Aviculipecten and not to Pecten, to Deltopecten, or to some other. The reference to Aviculipecten has therefore been made solely on general resemblances and probabilities.

Waagen and some other authors have attempted to distinguish between the Carboniferous Pecten and Aviculipecten by the relative size of the ears, whether the anterior ear was larger than the posterior, or the reverse; but the decision in regard to this point naturally hinges on the matter of orientation, in determining which I have noted much difference of procedure among different authors, or even in different decisions of the same author. I have tried to base my own determinations on the rule that the byssal notch is under the anterior ear of the right valve. Where the byssal notch is well developed this rule has worked well, but sometimes, owing to imperfections in the specimens or to the ambiguous character of the notch itself, there has been much uncertainty. It seems to be true that in most of the Carboniferous pectinoids the right or lower valve, in addition to having the byssal sinus, is also distinguished from the upper one by its less convexity and different sculpture, being as a rule nearly smooth or but imperfectly marked. Consequently, when I found a shell with strongly developed sculpture and the usual convexity I have called it a left valve, especially if there was no byssal notch or only an ambiguous sinus under the anterior ear.

The sculpture, however, seems not to hold as a distinguishing character for some of the Guadalupian Pectinacea. The shells placed under Camptonectes?, while having a deep byssal notch in the lower valve, are apparently equivalve, both in convexity and sculpture, and the Limas have both equal convexity and sculpture and are with out the byssal sinus.

From the foregoing remarks it will be apparent that the generic position of none of the Aviculipectens can be regarded as definitely determined, and therefore with this qualification I have omitted the query which should perhaps be placed after the generic title with all of them. These references to the genus, however, are probably as credibly based as is usual among Carboniferous pectinoids, where it is impossible, save in exceptional cases, to get at the hinge characters.

If I were to assemble these Guadalupian Aviculipectens into groups it would almost be necessary to assign each to a separate position. It would hardly be appropriate to refer A. laqueatus and A. sublaqueatus to the same group in the present state of our knowledge regarding them. The relations which A. guadalupensis, Aviculipecten sp. a, Aviculipecten sp. b, Aviculipecten sp. b var., and Aviculipecten sp. c bear to one another can not be precisely determined, since in the first two the shape but not the detailed sculpture is known and in the last three the detailed sculpture but not the shape. Provisionally, therefore, A. guadalupensis and Aviculipecten sp. a may be placed in one group and Aviculipecten sp. b, Aviculipecten sp. b var., and Aviculipecten sp. c in another. A. delawarensis and A. infelix would also have to be regarded as representing separate groups.

AVICULIPECTEN GUADALUPENSIS n. sp.

Pl. XVI, figs. 20 and 20a.

Of this species but two specimens have come to hand, the smaller and more perfect of which is selected as the type. Its characters of surface configuration and size are shown by the figures. The other example is considerably larger, and its length must have been not less than 32 mm. Both specimens are alike in having a large (anterior) ear without a byssal sinus. The other ear is more or less imperfect in both cases, but probably is as represented in the figure—narrow and without any trace of a sinus. This fact, together with the strong convexity, highly raised sculpture, and sharp demarcation of the ear which is preserved, indicate that the valve is a left one, in spite of the circumstance that this identification places the prolongation on the anterior instead of the posterior side. Oriented in this way Aviculipecten guadalupensis has the following characters:

Shell elongate. Hinge line long, but less than the width below. Convexity strong. Posterior ear probably consisting of a narrow lateral band, undefined by a sinus in the outline. Anterior ear marked off by an angular groove rapidly increasing in depth toward the margin. The cardinal line is of course on a level with the rest of the surface, so that this ear is inclined at a strong angle to the general plane of the shell. The anterior side is larger and more projecting than the posterior. The surface is marked by moderately coarse, sharply defined ribs, separated by interspaces of about the same size. They increase by implantation, and where new ones exist an alternating arrangement is apparent. There are about 20 in all. They diminish in size and strength toward the sides, but two or three large and strong ones occur on the anterior ear. The finer surface ornamentation is not known.

I rely on the anterior prolongation found in this form and the curious oblique position of the anterior ear to distinguish it from other species.

Horizon and locality.—"Dark limestone," Pine Spring, Guadalupe Mountains, Texas (station 2930).

AVICULIPECTEN sp. a.

Pl. XVI, fig. 21.

Only the right (?) valve is known of this species, and it shows the following characters:

The size is rather small, the convexity moderate, the shape elongate, slightly oblique, and projecting forward. The posterior ear is depressed, rather strongly defined on the surface, probably without a distinct sinus in the outline. The anterior ear is larger than the posterior, well defined on the surface and in the outline.

The surface is crossed by moderately fine ribs, which bifurcate and occur in pairs. The interspaces, which have about the same width as the ribs, are not strongly depressed. The finer ornamentation is unknown.

The orientation of this shell is a matter of uncertainty. I have described it as a right valve, because what would be the anterior ear, though not very perfectly preserved, appears to be defined below by a rather deep sinus, not, however, as profound as is often the case. On the other hand, the strength of the sculpture, the convexity, and the inclination of the axis all suggest that it is a left valve. If it is a right one, however, it differs sharply from most Aviculipectens, since with them the axis inclines backward and the right valve is almost flat and almost smooth.

This shell was found associated with Aviculipecten guadalupensis, and if really a right valve may prove to be the complement of the type of that species. The configuration rather lends itself to that interpretation, but the character of the sculpture is more or less unfavorable.

Horizon and locality.—"Dark limestone," Pine Spring (station 2930); basal black limestone, Guadalupe Point (station 2967 ?), Guadalupe Mountains, Texas.

AVICULIPECTEN DELAWARENSIS n. sp.

Pl. XXIII, figs. 2 and 2 a.

The configuration of this specimen, which is without any well-marked byssal sinus, indicates that it is a left valve. On this supposition the following description is based:

The shell is small and the curvature well rounded. The hinge line is long, but not so long as the greatest width. The posterior ear is undefined, the surface being merely flattened, without being crossed by a limiting groove. The anterior ear is strongly depressed and sharply defined by a groove. The outline gently contracts on this side from the extremity of the hinge to the line of depression which marks the ear, below which it widens strongly again. A rather marked anterior expansion is thus produced.

The surface is crossed by large, low, ill-defined and widely spaced ribs, and by faint, more or less irregular concentric liræ resembling strong growth lines. There is some evidence indicating that toward the ears these are strengthened at nearly equal intervals into low ridges.

This shell is similar to Aviculipecten? laqueatus, but the hinge line is relatively shorter, the posterior ear is differently shaped, and the sculpture lacks the concentric ridges which cancellate the surface of that species. It is possible that it may prove to belong to a different genus. It has much the configuration of typical Streblopteria, but I hesitate to refer it to that genus because of its plicated surface, though it is true that McCoy includes radially ribbed species with Streblopteria lævigata.

Horizon and locality.—Delaware Mountain formation, Guadalupe Point, Guadalupe Mountains, Texas (station 2931).

AVICULIPECTEN sp. b.

Pl. XXXI, fig. 8.

This species is discriminated on the basis of a fragment which shows the surface ornamentation almost perfectly, but from which the original shape can only be surmised. It was probably rather elongate and narrow beneath the auricles. The surface is well exhibited by the illustration and need not be described in detail, The ribs are relatively coarse and strongly elevated, nearly equal, but slightly alternating. About seven occur in 10 mm. On their crests are prominent vertical scale-like projections, six in 5 mm. The spaces between the ribs are deeply depressed, and have the same width. They are marked by rather regular, somewhat imbricating concentric lamellose liræ, which are much smaller than the scales surmounting the ribs, and entirely independent of them. A few small intermediate ribs of the same general character occur at the side of the larger ones.

Horizon and locality.—Delaware Mountain formation, Comanche Canyon, Glass Mountains, Texas (station 3763).

AVICULIPECTEN sp. b var.

Pl. XXXI, fig. 9.

This species is evidently related to Aviculipecten sp. b and was found associated with it. The fragment representing it indicates a smaller and more highly arched species. The ribs, and especially the concentric rows of scales which occur upon them, are finer. There are more abundant indications of fine intermediate ribs, and therefore the intercostal spaces are filled by radiating lines of little scales obscuring the concentric liræ, which probably mark them, as in the other variety, and form the bases from which the scales are developed.

Horizon and locality.—Delaware Mountain formation, Comanche Canyon, Glass Mountains, Texas (station 3763).

AVICULIPECTEN sp. c.

Pl. XXXI, fig. 10.

The ornamentation of this species is a development of the same character as in the two preceding ones, but somewhat removed from them. The ribs are in groups of three for the most part, the middle one much raised, with a smaller one on each side. The concentric rows of scales which surmount the ribs are smaller and less prominent, and the concentric liræ on the interspaces appear to consist of much smaller scales, which form fine radiating rows. The general character of the surface is shown by the figure.

Horizon and locality.—Delaware Mountain formation, Comanche Canyon, Glass Mountains, Texas (station 3763).

AVICULIPECTEN INFELIX n. sp.

Pl. IX, figs. 9 to 10.

Of this type only five specimens are known. They all have essentially the same shape, so far as their preservation, which is for the most part poor, permits a comparison, and appear to represent the same valve, which I take to be the right one. On this supposition the following description cam be given.

Shell small, length greater than breadth, erect or slightly inclined backward, cardinal line rather short. Ears nearly equal, quadrate, or somewhat extended. They are defined by reentrant angles on the outline and by grooves on the surface. The groove defining the anterior ear is more marked than that of the posterior. While without the deep byssal notch and specialized configuration of the anterior ear which is found in some species, the one ear is considerably more sharply defined than the other, and on this account I have regarded it as being the anterior ear of the right valve. The convexity is low. The inferior margin is broadly rounded.

Except for indistinct concentric markings, the surface is plain, without radiating ribs on any portion.

The generic and specific relations of these shells are alike uncertain. Their erect shape, smooth surface, and nearly equal ears are unlike the typical characters of either Pecten or Aviculipecten. Either ear is too small and well defined to be the larger ear of Streblopteria. Possibly their closest allies are to be found in Pseudamusium and Syncyclonema. They are readily distinguished from the forms described under Camptonectes? by their outline, low convexity, and smooth surface. They more strongly resemble Pernipecten? obliquus, from which at first I did not successfully distinguish them. By reason of their somewhat different configuration and because they always lack the upturned superior lateral margins, which are so distinctive of Pernipecten and are more or less well shown in P.? obliquus, they appear to differ from the latter species.

Horizon and locality.—Middle of Capitan formation, Capitan Peak, Guadalupe Mountains, Texas (station 2926).

AVICULIPECTEN LAQUEATUS n. sp.

Pl. IX, fig. 11.

Only one specimen of this species has come to hand, which appears to be a left valve. Its characters are as follows:

The size is about medium, the convexity moderately high. The hinge line is long, as wide or a little wider than the width below. The ears are large, the anterior somewhat larger than the posterior, more strongly defined, and differently shaped. The outline is retracted below the ears, but widens again, especially on the anterior side, which appears to be somewhat projecting.

The surface is marked by regular, strong, concentric and radiating ridges, somewhat widely spaced, the concentric ones being more distant than the radiating. The effect of this ornamentation is to divide the surface into depressed panel-like areas, of which the length, especially toward the margins, is considerably in excess of the width. There are also sublamellose concentric liræ closely but somewhat irregularly arranged.

From the character of the ears this can hardly be a right valve. As a left valve it differs from typical Aviculipecten in having the anterior ear larger than the posterior, in having an anterior prolongation of the body of the shell, and in the character of its surface ornamentation. The anterior ear is unusually depressed and sharply defined, the limiting groove being so strongly reentrant that the body of the shell overhangs the oral angle.

Horizon and locality.—Middle of Capitan formation, Capitan Peak, Guadalupe Mountains, Texas (station 2926).

AVICULIPECTEN SUBLAQUEATUS n. sp.

Pl. IX, fig. 12.

The shape and general expression of this species are very like those of Aviculipecten laqueatus, but the size, as indicated by our fragmentary specimen, is much greater and there are important differences in the sculpture.

Only the left valve is known. The hinge line is long, the ears large and depressed, the anterior smaller than the posterior, and defined by both a deeper and a more abrupt descent from the arched portion of the shell. There is but a gentle sinus under the posterior ear.

The surface is marked by moderately strong ribs, spaced at nearly equal but wide intervals from one another. In the figured specimen there are but six of these, and they probably remained constant in number throughout the entire growth. Intermediate between the large ribs are other much finer ones. These increase in number with the size of the shell. There are also concentric lines somewhat more closely arranged than the larger ribs, so that the surface is divided into transverse panels. On the figured specimen, which is an internal mold, these concentric markings are distinct striæ, which have the upper side slightly more elevated than the lower. On the external cast they are seen to be produced not so much by lamellæ as by steplike differences in elevation of the shell surface, which are produced into squamose spines where they cross the ribs. The latter at such points tend to become nodose.

A large fragment referred to this species indicates a length of not less than 50 mm. It is conspicuously crossed by three rapidly diverging ribs, which at the margins are 15 mm. apart. They are coarse and marked at intervals of about 7 mm. by strong nodes. Between two of the large ribs there are from 10 to 20 more or less wavy radiating liræ of very much smaller size. In smaller specimens the radiating liræ are only five or six in number, and probably when very small they are reduced to a single one and are indistinguishable from the real costæ.

The nearest Guadalupian species to the present form is unquestionably A. laqueatus, which is distinguished by having more numerous ribs and concentric instead of radiating liræ. The concentric liræ are so distinct that it seems impossible that radiating ones, had they ever been present, could have been destroyed.

A. sublaqueatus resembles A. mccoyi somewhat closely, but is distinguished by its broader posterior ear and finer, more numerous and equal intermediate ribs. In these particulars it resembles Acanthopecten carboniferus, but of course is readily distinguished by its less numerous costæ.

Horizon and locality.—Middle of Capitan formation, Capitan Peak (station 2926?); base of Capitan formation, hill southwest of Guadalupe Point (station 2906), Guadalupe Mountains, Texas. Delaware Mountain formation, Comanche Canyon, Glass Mountains, Texas (station 3763).

Genus ACANTHOPECTEN Girty.

ACANTHOPECTEN aff. A. CARBONIFERUS Stevens.

In the yellow sandstone of the Delaware Mountain formation (station 2931) was found a specimen representing part of a mold of the exterior of a shell probably belonging to a type closely allied to Acanthopecten carboniferus Stevens. The species was apparently considerably larger than A. carboniferus, with larger and more numerous ribs, of which about two came in the space of 5 mm. in the fragment preserved. The spinous concentric lamellæ, however, were more closely arranged, being from 2 to 2-1/2 mm. apart. No further details are shown by the imperfect example.

Horizon and locality.—Delaware Mountain formation, Guadalupe Point, Guadalupe Mountains, Texas (station 2931).

Genus EUCHONDRIA Meek.

EUCHONDRIA? sp.

Pl. IX, figs. 8 and 8a.

Only one specimen of this form has thus far been found, and its general character is shown by the illustrations. It is uncertain whether it is a right or a left valve, as one of the ears is imperfect. The general appearance is that of right valves of Camptonectes? papillatus and C.? asperatus; and because the imperfection above alluded to may have destroyed the character which distinguishes right valves of those species, there is no way of telling that it is not one of them. The present specimen is nearly or quite an internal mold, so that the surface can not be used as a criterion. If it is a right valve, the posterior ear is distinctly larger and better defined in proportion to its size than that of typical examples of the species mentioned, though as the specimen is a very small and probably a young one, these departures from the typical character may really be due to immaturity. On the other hand, if the valve proves to be a left one, as its axial inclination might suggest, it is probably a Euchondria and related to the little shell which Waagen described as E. subpusilla.

In view of this uncertainty about very fundamental points I do not feel justified in giving this form a name, though if it is really congeneric with E. subpusilla there is little doubt that it represents a new species.

Horizon and locality.—Middle of Capitan formation, Capitan Peak, Guadalupe Mountains, Texas (station 2926).

Genus PERNIPECTEN Winchell.

PERNIPECTEN? OBLIQUUS n. sp.

Pl. IX, figs. 13 to 14a.

Shell small, elongate, nearly flat. Hinge line shorter than the width below. In the left (?) valve the two ears are nearly equal, small, and moderately well defined both in outline and by grooves on the surface. The shell expands considerably below them, and is gently inclined backward (?). The superior portion is more or less turned upward at the sides along two converging lines.

The surface is rather regularly marked by delicate concentric striæ.

Only one valve seems to be represented in our collections, and the foregoing description is applicable to about half a dozen specimens from the Capitan limestone, but all of them are, unfortunately, imperfect. The smooth surface, the low convexity, and the upturned margins of these shells seem to ally them with Entolium and Pernipecten; but the obliquity of the axis and the small extension of the ears, if, indeed, the shape is that which seems to be indicated by my imperfect material, are unusual among those forms.

The low convexity of these shells would distinguish them from any of the other pectinoids of this horizon except Aviculipecten infelix, even if the sculpture and conformation did not offer additional characters for discrimination.

A single imperfect example from the Delaware Mountain formation has been provisionally referred to the same species.

Horizon and locality.—Middle of Capitan formation, Capitan Peak (station 2926); Delaware Mountain formation, Guadalupe Point (station 2931), Guadalupe Mountains, Texas. Delaware Mountain formation, southern Delaware Mountains, Texas (station 2935).

Family LIMIDÆ Fischer.

This family is represented by two rather distinct types of shells. They are alike in having a high convexity, in being equivalve both in curvature and in sculpture, and in having a byssal sinus in neither valve. They differ in the fact that one is perfectly smooth and the other is adorned with radial sculpture, though the lateral portions are smooth. Both can be referred to the genus Lima, the former to the group which has been called Plagiostoma, the latter to Limatulina. Strictly speaking, Plagiostoma and Limatulina must be considered subgenera of Lima, but I have, for the sake of brevity, cited them independently, as if of full generic rank, a course which certainly would not have been adopted had the present work more of a systematic and less of a stratigraphic or faunal purpose.

To Limatulina will also have to be assigned our characteristic Coal Measures species Limatulina retifera. Plagiostoma is not yet known in the Pennsylvanian, but seems to be a frequently recurring factor in the German Dyas and the English Permian.

Genus PLAGIOSTOMA Sowerby.

PLAGIOSTOMA DELTOIDEUM n. sp.

Pl. IX, figs. 15 to 16a.

The two valves of this species are so alike that a description of one of them applies equally well to another, the necessary allowance being made for the reversal of the parts.

The general appearance of these shells is that of a Nucula, but the presence of two inconspicuous ears shows that the generic relations are widely different. The ears are not defined in any way, being merely a flattening and extension of the otherwise arched shell. The posterior ear especially is extremely small and ill defined. The anterior and posterior outlines are nearly straight, the latter being much longer than the former. The lower margin is broadly curved, and the axis is rather strongly inclined to the cardinal line. The surface is nearly smooth, being marked only by very obscure concentric striæ.

Two right and three left valves from the Capitan formation represent this species, while a single left valve from the black limestone at the base of the section has been provisionally referred to it. The latter specimen has a length of 10 mm., and is considerably larger than anything yet obtained from the Capitan. Its characters are imperfectly known, but it agrees with P. deltoideum in many points, the only differences detected being apparently unimportant.

Horizon and locality.—Middle of Capitan formation, Capitan Peak (station 2926); basal black limestone, Guadalupe Point (station 2920?), Guadalupe Mountains, Texas.

Genus LIMATULINA Wood.

LIMATULINA STRIATICOSTATA n. sp.

Pl. IX, figs. 17 to 19.

Although my material is both scanty and fragmentary, I have ventured to describe this species and give it a new name, because it is so interesting and pretty.

Shell small, rather strongly oblique, narrow. Hinge line short. Anterior side nearly straight, posterior side probably very much rounded.

The surface is marked with moderately strong, more or less angular plications, having broad, flattened spaces between them. Four or five plications occur within the linear distance of 2 mm., and the entire shell probably contained not far from 25. The whole is crossed by delicate, rigid, superficial, radiating liræ, and concentric markings, more or less obscure, which partake of the nature of growth lines. Both anterior and posterior sides are smooth, lacking plications and also, probably, superficial liræ.

Both valves appear to have the same characters of configuration, though of course in some cases reversed by being symmetrical.

This species resembles L. retifera in having a band on both sides devoid of plications. On this account, and also because there is little evidence that the valves gap behind, these species seem more closely allied to Limatulina than to Lima sensu stricto. At the same time I have not seen any traces of the area which distinguishes both of these genera. In fact, in some examples this structure seems to be wanting.

L. striaticostata is distinguished from L. retifera and many other members of the genus by the fine radial striation surmounting the ribs. The small specimen represented by fig. 19 shows these striæ very well preserved, but they are somewhat finer than in the other examples, a fact which, joined with this other—that the plications also are somewhat different—may indicate a varietal or even a specific difference.

Horizon and locality.—Middle of Capitan formation, Capitan Peak, Guadalupe Mountains, Texas (station 2926).

Family MODIOLOPSIDÆ Fischer.

Genus MYOCONCHA Sowerby.

This genus is represented by two species, only one of which is at all well known, and even of it our knowledge is only partial. Their reference to Myoconcha, therefore, is not made with any degree of confidence. Indeed, owing to the lack of definite knowledge on several features of importance I seem to see resemblances to two very distinct groups of pelecypods. The supposed relationship to the Modiolopsidæ is expressed in the generic reference above, but I am not sure that the affinities of these forms are really not with the Pleurophoridæ. They are more rapidly expanding than most species of Pleurophorus, which as a rule have the upper and lower margins more or less parallel, and their costæ are developed on the anterior instead of on the posterior half of the shell; but in some respects, both external and internal, they are very suggestive of Pleurophorus.

MYOCONCHA COSTULATA n. sp.

Pl. IX, figs. 21 to 21b.

In the Capitan limestone two specimens belonging to this species have been found. They seem to be alike in all characters observed, and the left valve, which is in better preservation, is taken as the type.

Shell small, subovate, strongly convex, very oblique, and inequilateral. Hinge line long, straight, shorter than the height, which is in turn shorter than the greatest diameter; that is, along the diagonal. Anterior and posterior sides nearly rectilinear, parallel, and directed to the hinge line at an angle of about 130°. Posterior-inferior outline broadly rounded. Umbo nearly terminal, but with a small anterior lobe.

The surface is crossed by a few coarse, obscure, radiating plications, which are largely confined to the anterior third of the shell. As the specimen is an internal mold, this feature was probably more distinct on the outside. Two angular lines of flexure radiating from the umbo divide the shell into three more or less equal parts. In the anterior one, two small and two large ribs occur, while the large, sharply defined muscle scar probably indicates a small anterior lobe. The middle division has a few almost invisible costæ, while the upper is without this feature altogether. In the mold there is a flattened, depressed band along the hinge line sharply separated from the rest of the shell. This band narrows gradually toward the umbo, and in a large specimen to be mentioned later it contains the impression of a long posterior tooth having a groove above it. I have seen no evidence of a cardinal tooth, a structure which real examples of the genus ought to possess.

Horizon and locality.—Middle of Capitan formation, Capitan Peak, Guadalupe Mountains, Texas (station 2926).

MYOCONCHA COSTULATA var. DELAWARENSIS n. var.

Pl. XXIII, fig. 3.

In the Delaware Mountain formation several specimens have been found which are evidently related generically to Myoconcha costulata, and they also resemble it in some specific characters. Two specimens especially deserve consideration a third being too imperfect for further notice. Their shape would not distinguish them satisfactorily from M. costulata, but all three have a distinctly lower convexity and lack the radiating ribs of that species. In the larger specimen especially it would be expected that the ribs would be indicated had they ever been present, for the preservation is not so much that of an internal mold as in the one from the white limestone, and even clearly shows traces of irregular concentric striæ, though nothing in the nature of ribs can be detected. It is probable that other characters will appear when better examples are studied, and that even the shape of the variety delawarensis will be found to be distinguishable; but at present the low convexity and lack of ribs are relied on to discriminate this variety from M. costulata.

Horizon and locality.—Delaware Mountain formation, Guadalupe Point, Guadalupe Mountains, Texas (station 2931).

Family PLEUROPHORIDÆ Dall.

Genus ASTARTELLA Hall.

ASTARTELLA NASUTA n. sp.

Pl. XXIII, figs. 6 to 7a; Pl. XXXI, figs. 12 and 12a.

Shell rather small. Shape, exclusive of the anterior projection, nearly square, the upper and lower margins being approximately parallel, the posterior almost perpendicular to them, and all three nearly equal in length. The lower part of the anterior end is strongly projecting.

The surface is marked by strong, closely arranged, rather regular lamellæ. The internal characters are as in Astartella vera.

The typical specimen is a left valve from the Glass Mountains, but we have also two left valves from the Delaware Mountain formation of the Guadalupe section, which appear to belong to the same species. The shape is similar, and the surface, though preserved as an internal mold, is crossed by concentric corrugations, indicating the presence on the outside of projecting lamellæ. The surface ornamentation of this species is not unlike that of A. concentrica Conrad,a though for its size rather coarser and more crowded. It is distinguished from most species of Astartella, however, by its narrow shape, more nearly parallel superior and inferior margins, and its projecting or nasute anterior extremity. It more nearly resembles in shape A. gurleyi, from which it differs in being larger, more nasute, and in having the lamellæ of the surface much coarser and more projecting.

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aFive species of Astartella are listed in Weller's catalogue, to which must be added a sixth—Nuclites concentricus Conrad (Jour. Philadelphia Acad. Nat. Sci., Sat ser., vol. 8, 1842, p. 248). This was correctly referred to Astartella by Meek as long ago as 1875 (Paleontology of Ohio, vol. 2, p. 541), but Conrad's publication being rare it seems to have been but little cited. Several of the six species are clearly valid, but others are more doubtful. There can be but little doubt in regard to Astartella varica and A. gurleyi. Recently (Prof. Paper U. S. Geol. Survey No. 16, 1903, p. 45) I suggested that the latter species might be a Microdon. An examination of characteristic examples from Danville has convinced me that that suggestion was without foundation in the case of the typical form, whatever may be said with reference to the one from Colorado in connection with which the observation was made. A. concentrica Conrad, A. concentrica McChesney, A. newberryi Meek, and A. vera Hall are more in doubt. A. concentrica McChesney seems to be distinct from the other species, partly because of its shape, but more especially because of the surface ornamentation which McChesney describes. As the name was preoccupied by Conrad, Astartella mechesneyi is proposed to replace it. Meek regarded A. newberryi as distinguished from A. concentrica Conrad by certain points in its configuration; but I believe that the two species will prove to be in fact the same. A. concentrica, A. newberryi, and A. vera resemble one another closely in shape, but probably a valid distinction can be based on the character of surface ornamentation. Hall's description applies equally well to the two other species mentioned, but it at once differs from his figures and from the observation of Meek, who compares A. newberryi with A. vera. In a varied collection examined by me a few shells agree with Hall's figure and differ from the majority of material in having the liræ more irregular and not so prominent, the points in which Meek states A. vera to differ from A. newberryi. It seems to me therefore that A. vera can be accepted as valid, on account of its surface characters. A. concentrica and A. newberryi will probably prove to be the same; and to the former, which has priority by many years, the rest, and by far the major portion, of our collection would belong. It is not impossible, however, that A. concentrica, A. mechesneyi, A. newberryi, and A. vera will be resolved into one or into varieties of one species.

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This species appears to be closely related to Astarte permocarbonica Tschernyschew of the Russian Permian.a

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aVerhandl. Russ. k. min. Gesell. zu St. Petersburg, 2d ser., vol. 20, 1885, p. 276, pl. 15, fig. 10.

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Horizon and locality.—Delaware Mountain formation, Guadalupe Point, Guadalupe Mountains, Texas (station 2931). Delaware Mountain formation, Comanche Canyon, Glass Mountains, Texas (station 3763).

Genus CYPRICARDINIA Hall.

CYPRICARDINIA? CONTRACTA n. sp.

Pl. IX, figs. 23 and 23a.

Shell small, highly inflated, subcuneate. Hinge line straight, about as long as the posterior margin, which is gently curved and merges at either end with the upper and lower borders. Beak near the anterior extremity, but with a very marked lobelike projection anterior to it.

Surface marked by regular, heavy, concentric, imbricating lamellæ, each of which bears indications of an independent set of coarse radiating ribs.

Of the interior of the shell but little is known. There was a relatively broad, flattened, more or less lamellar area along the hinge line, and a large deep muscle scar on the anterior lobe.

The general appearance of this shell somewhat suggests Cypricardinia, though the shape is more cuneate than in typical forms. The surface ornamentation, consisting of heavy overlapping lamellæ, with radial markings, is also very like Cypricardinia, but it is not probable that these markings are cancellate, as is frequently the case in that genus, nor do the internal characters agree very well with Cypricardinia, though they are too imperfectly known to be trusted. On the whole it seems rather unlikely that this shell will be found to be a true Cypricardinia, but it is impossible with the material at hand to ascertain its generic position. In its specific relations it is evidently quite distinct from C. carbonaria, the only Pennsylvanian member of the genus known at this time.

The type specimen of this species is a right valve from the white limestone of the Capitan formation, but two other specimens probably representing the same species—also right valves—have been found in the Delaware Mountain formation.

Horizon and locality.—Middle of Capitan formation, Capitan Peak, Guadalupe Mountains, Texas (station 2926).

Genus PLEUROPHORUS King.

PLEUROPHORUS DELAWARENSIS n. sp.

Pl. XXIII, fig. 4.

Shell large, very transverse. Upper and lower margins contracting toward the anterior end. Posterior superior angle about 130°. Posterior outline nearly straight above, broadly rounding to the lower margin. The latter is nearly straight, with perhaps a gentle sinus forward of the middle. Umbo moderately elevated. Anterior end below the beak projecting. Convexity (which may have been diminished by compression) low.

Surface without radial angulations, marked by fine concentric striæ.

The left valve on which this description is based is preserved as a partial internal mold, retaining some of the external as well as the internal characters. Since some of the concentric striæ are shown it is unlikely that radial ribs or angulations, had they ever been present, would have failed of preservation.

This species resembles both Pleurophorus oblongus and P. subcostatus. It is, however, much larger than either, and differently shaped, having also different surface characters from the species last mentioned.

Horizon and locality.—Delaware Mountain formation, Guadalupe Point, Guadalupe Mountains, Texas (station 2931).

PLEUROPHORUS sp.

At station 2964, in the southern Delawares, what is probably a species of Pleurophorus appears to be fairly abundant. My specimens are very imperfect, however. The form appears to resemble P. calhouni Meek and Hayden, but the specific as well as the generic relations are as yet almost conjectural.

Horizon and locality.—Delaware Mountain formation, southern Delaware Mountains, Texas (station 2964).

Genus CLEIDOPHORUS Hall.

There seems to be much diversity of opinion regarding the affinities of this genus. Perhaps the majority of writers have regarded it as related to Pleurophorus, and this was, I believe, the opinion of Hall himself. Dall, in the American Zittel, places it among the Ledidæ. Whatever may be the position of typical Cleidophorus, I am not without excellent precedent for referring to that genus the type of shell which is here placed there, and that, there can be no question, is not one of the Ledidæ.

CLEIDOPHORUS PALLASI var. DELAWARENSIS n. var.

Pl. XXIII, figs. 5 and 5a.

This form is represented by a small specimen from the Delaware Mountain formation preserved as an internal mold. The general shape is subtriangular. The cardinal line is slightly convex. The inferior outline is gently concave, or perhaps sigmoidal, and directed to the cardinal outline at an angle of about 45°. The posterior outline is also gently curved, very oblique, joining the inferior outline in a strong curve, and gradually merging into the cardinal outline. The anterior extremity is abruptly rounded, modified by the almost terminal beak and the small anterior lobe. The convexity is considerable, the umbonal ridge being near the lower border and the slope above much less abrupt than that below.

The surface appears to have been marked by concentric striæ, but ribs were probably absent, for they do not appear on the internal mold, as they probably would had they been present, since the shell appears to have been thin and delicate.

The character of the dentition is only partially known. The shell appears to have been thickened along the hinge line and to have borne a longitudinal groove, probably for a ligament. Posteriorly, parallel to this, and just below it, was a deep, narrow socket for a linear posterior tooth borne upon the left valve.

This form appears to be related to Cleidophorus pallasi De Verneuil from the Russian Permian, but is distinguished by slight differences in shape, which in view of its geographical and faunal occurrence seem to me to demand at least a varietal discrimination. The resemblance appears especially with De Verneuil's figures, other authors, such as Netschajew and Golowkinsky, having referred forms to that species in which the resemblance is less apparent. Some of Geinitz's figures of C. pallasi represent a shell with radiating ribs.

Horizon and locality.—Delaware Mountain formation, Guadalupe Point, Guadalupe Mountains, Texas (station 2931.)

INCERTÆ SEDIS.

Genus PROTRETE n. gen.

After much hesitation it has seemed necessary to introduce for the Guadalupian type here described a new generic name, for to have retained it under either of the several genera with which I thought at different times to assemble it would have been confessedly a makeshift.

The shape is more or less modiliform, very transverse, slightly higher in front than behind, but with subparallel upper and lower margins. The beaks are nearly terminal. The two valves are equal and closed all round. Just under the beaks, however, there is a tubular perforation excavated in the substance of both valves. The dentition is not known with certainty, but there appear to be neither cardinal nor anterior teeth. In the left valve the long hinge line is thickened and longitudinally indented by a median groove. This may be the position of a resilium. At the same time there is an obscure estucheon on the outside of the cardinal line, as if for an external ligament.

I had some thought that the tube which opens beneath the beaks in this form might be a depressed lumule, such as I have observed in Pleurophorella, but it seems to be a real opening into the interior of the shell. Even if it were a depression merely I would feel indisposed to refer this form to Pleurophorella, because of the absence of the characteristic sculpture of radial ribs and of papillæ.

Superficially this type resembles some of the Paleozoic shells which it has been customary to place with Lithodomus, but the anterior opening distinguishes it from that genus as well as from all others suggested by its shape. There is but little likelihood, however, that it belongs with Lithodomus, which is now regarded as a synonym of Lithophagus.

PROTRETE TEXANA n. sp.

Pl. XXIX, figs. 12 to 13.

Shell small, very transverse. Height of the typical specimen a little less than 4 mm., width a little more than 8 mm. Upper and lower margins subrectilinear, subparallel. The upper one is slightly convex and the lower slightly concave, and they converge gently toward the front. Anterior end abruptly rounded, posterior end very obliquely truncated, the outline above merging gradually into that of the cardinal line, below abruptly rounding into coincidence with that of the inferior margin. Umbones small, incurved, nearly terminal. Convexity greatest in front, flattening behind. Umbonal ridge poorly defined.

Surface marked by a few strong imbricating lamellæ.

Horizon and locality.—Delaware Mountain formation, southern Delaware Mountains, Texas (station 2969).

SCAPHOPODA.

This group, while beginning early in geologic time, is rare among most Paleozoic faunas and possesses little significance, not only on this account, but because the minute characters of the smaller end, on which chiefly the classification is based, can be observed in few specimens from that period.

In the Guadalupian fauna only one species of this group has come to hand. Its horizon is restricted to the Delaware Mountain formation, where it is moderately abundant. No sculpture is shown by the Guadalupian specimens, and it is not a certainty that they belong to White's species. There is, furthermore, some doubt as to whether Dentalium canna, as based on the typical specimens, is a Lævidentalium or a Plagioglypta. It is almost certainly not a Dentalium in the strict sense.

Scaphopods appear only very sporadically in the faunas with which I have compared that from the Guadalupe Mountains. In the Salt Range Waagen found one species of Entalis and fragments of two species of Antale?. The Entalis might well belong to the same genus as the Guadalupian form, except for the fact that it is slightly curved. It is distinguished by its gigantic size. Enderle found the same species at Balia Maaden. Stuckenberg cites Dentalium sp. from the Gschelian, but does not figure it. From the Artinsk he cites Dentalium speyeri, apparently a Lævidentalium or a Plagioglypta not closely related to the Guadalupian form. Krotow cites from the Artinsk, without figures, Dentalium priscum and D. varicosum. Netschajew cites D. speyeri and Entalis cf. prisca from the Russian Permian. Both species seem to resemble Plagioglypta canna in a general way, and Entalis cf. prisca may prove to be a Plagioglypta. Gortani cites this species (Entalis prisca) from the Carnic Alps. His figure is rather poor, but appears to represent a species related to P. canna. In the Dyas Geinitz found Dentalium sorbii and D. speyeri. The latter, which alone is figured, seems to be a smooth form like P. canna, but small and curved. King described from the English Permian Dentalium sorbii, apparently another form belonging to Plagioglypta or Lævidentalium.

In the Pennsylvanian a similar type of shell seems to be found in Plagioglypta meekana, but it is somewhat uncertain whether if the Guadalupian form were better known the relationship would be unquestioned. I have identified the Guadalupian species with P. canna, a type which is abundant in the Aubrey sandstone of Arizona and New Mexico, but the identification is a rather doubtful one. The Guadalupian specimens are poorly preserved and some of the characters of P. canna are not recognizable on them. The associated faunas are so different, furthermore, as to make me offer the identification with reserve.

Family DENTALIIDÆ Gray.

Genus PLAGIOGLYPTA Pilsbry.

PLAGIOGLYPTA CANNA White?

Pl. XXIII, figs. 11 to 13.

This species is fairly common in the Delaware Mountain formation, but thus far has not been obtained from any other horizon. The figures afford an idea of the characters shown by our specimens. It is a gradually tapering shell, nearly if not quite straight, and complete examples must have been of considerable size. The largest diameter shown is 9 mm. The surface was nearly smooth. None of the external molds show markings, and in this point they differ from the typical specimens, though the delicate sculpture found on the latter may easily have failed of being retained by the sandy matrix in which the Guadalupian specimens are held. Otherwise the Guadalupian form has every character of the types.

White restores this species as very distinctly curved, but the type specimens are seemingly straight, while the Guadalupian specimens, if they are correctly assigned to the species, indicate that the curve, if present at all, was imperceptible. White also both figures and describes the shell as superficially marked by obscure longitudinal lines. These markings, if present on the types, are at least so obscure that I can not see them. The slightly oblique encircling lines are plain, but I can detect no longitudinal markings which it would be safe to interpret as sculpture. On this account it would be well to remove this species from the genus Dentalium. In 1903 I referred it somewhat doubtfully to Plagioglypta, and in retaining the same usage in this place I retain also the same doubts. It may be a Lævidentalium.

Horizon and locality.—Delaware Mountain formation, Guadalupe Point, Guadalupe Mountains, Texas (station 2931).

AMPHINEURA.

Family GRYPHOCHITONIDÆ Pilsbry.

Genus CYMATOCHITON Dall.

The Amphineura are usually rather rare in the Paleozoic, and consequently do not serve an important function in characterizing or correlating horizons. They seem to be abundant in the late Carboniferous of Europe, however, and with the latter the Guadalupian form serves as some sort of a link.

Stuckenberg and Krotow cite Chitonellus antiquus Howse from the Artinsk, but I have not seen the group recorded from the Russian Permian. In the Dyas of Germany, however, it appears to be represented. Geinitz cites four species of Chiton and three species of Chitonellus. The latter are entirely unrepresented in the known Guadalupian fauna, and the Chitons are not closely related to Cymatochiton? texanus.

The English Permian has furnished Chiton loftusianus, a form which is probably not congeneric with that from the Delaware Mountains. The latter, I may add, is doubtfully referred to Cymatochiton. The large size of the sutural laminæ, in addition to other peculiarities, makes its reference to that, or, in fact, to any of the genera known in the Carboniferous, somewhat questionable. With only a single plate, however, the determination of its generic relations can not be successfully accomplished.

In the Pennsylvanian fauna no Chitons have as yet been discovered.

CYMATOCHITON? TEXANUS n. sp.

Pl. XXIX, figs. 21 and 21a.

Of this type, which seems to be so common, relatively speaking, in the Permian of Europe, the Guadalupian collections have furnished but a single specimen. The shape is transversely pentagonal, the sides being short and nearly parallel. The two upper margins are slightly sigmoidal in outline and meet in an angle of about 90°. The lower margin also consists of two lines, nearly rectilinear, but slightly sigmoidal, and meeting in a gentle projection. Longitudinally the curvature of the plate is very slight, transversely it is rather strongly convex, the convexity, however, being in the nature of a dihedral angle whose sides are nearly flat. The sutural laminæ are very long. The surface appears to have been smooth.

The group of forms to which this species belongs is not at present known from the American Pennsylvanian, but is fairly abundant in the European Permian. From the species of the latter fauna which I have seen the present form differs in being less transverse and in having much longer sutural laminæ.

Horizon and locality.—Delaware Mountain formation, southern Delaware Mountains, Texas (station 2969).

GASTEROPODA.

While far less abundant than the brachiopods, gasteropods show an unusual diversity and play an unusually important role in the Guadalupian fauna. Forty-two varieties have thus far been distinguished, and as each new collection contains specimens which, though usually few in number, belong for the most part to undescribed species the measure of variations presented by this group has not yet been taken. The Pennsylvanian fauna in the aggregate also contains a large number of gasteropod species, but in individual collections they are certainly no more abundant than in the Guadalupian and tend much more to repeat a few common types.

The known Gasteropoda of the Guadalupian have been assigned to 15 genera, but by far the larger portion belong to the Pleurotomariidæ. According to the generic determinations made below, some of which are recognized as being doubtful, this group, embracing the genera Murchisonia, Euconospira, and Pleurotomaria itself (under which title are probably included representatives of several subgenera, although the information obtained regarding many of the forms is not such as to favor further subdivision) comprises 24 out of the 42 species. The Bellerophons, has seemed to me desirable to make, so far as practicable, an adequate presentation of this division of the fauna, and so far as the data were at hand accounts more or less complete have been given of about 40 species, as previously remarked. At the same time a few varieties have been passed over. A considerable percentage of the species described have been left unidentified and unnamed, the data at hand in my judgment indicating differences from described species without conveying facts adequate for the establishment of new ones. Even in some cases where new names have been proposed, the specific characters have not been shown as clearly or as completely as I could wish.

In the Salt Range fauna Waagen recognized 34 gasteropod species, representing 16 genera, but in great contrast to the Guadalupian fauna nearly two-thirds of these, or 23 species, belong to the Bellerophontida.

In general the Salt Range and Guadalupian faunas have very little in common, most of the genera even being different. The two Salt Range species of Euomphalus are not very closely related to the two Guadalupian ones. The genus Holopella seems to be absent from the Guadalupian fauna. Waagen's Macrocheilus is the same as my Macrocheilina, and the single Indian species in its essential characters is not so very different from those of my fauna, though this genus at best does not show any very great differentiation. The genus Naticopsis finds one Guadalupian representative, which, specifically at all events, is distinct from either of the Salt Range species, but is somewhat related to N. khurensis. It is rather more suggestive of the single species which Waagen described under Platystoma. Neritomopsis, of which Waagen recognized two species, is not known in the Guadalupian, and the same is true of the genera Phasianella and Margarita. The four Pleurotomarias of the Salt Range fauna are related to certain of the numerous varieties from the Guadalupe Mountains, which present, however, many that are different. The single Salt Range species of Murchisonia also resembles in a very general way the two imperfectly known Guadalupian ones.

Waagen found nine species of Bellerophon in the Salt Range fauna, as against one in the Guadalupian. All are naturally of the same general type, some of the Salt Range species resembling the Guadalupian B. crassus more particularly and others less. Four species of Bucania are found in the Salt Range, comprising in part at least the same group for which I have employed the name Bucanopsis. B. kattaensis, B. integra, and B. angustifasciata appear to be of the same general type as the Guadalupian species. The fourth, B. ornatissima, has no Guadalupian equivalent. The peculiar Salt Range genera Mogulia and Stachella, together with Euphemus, a common type in our Pennsylvanian, are not known in the fauna of the Guadalupian Mountains, but the Salt Range genus Warthia has been identified there. On the other hand, the Guadalupian fauna contains representatives of Patella, Bulimorpha, Pseudomelania, Turbo?, Trochus?, and Loxonema, besides several types of Pleurotomaria not known in the Salt Range. Thus the comment with which this hasty comparison of the two faunas set out seems to be justified, for they do not appear to show a close relationship in point of the gasteropod class. The most noteworthy differences are the much greater development of the Pleurotomarias in the Guadalupian and the much greater development of the Bellerophons in the Salt Range fauna.

Gasteropods seem to be rare in the Himalaya, for Diener's reports contain scarcely any mention of them. I find an unidentified species of Naticopsis noted in his second paper on the Chitichun fauna No. 1, and a few species are cited from Malla Sangcha, the Lissar Valley, and Byans, as follows: From Malla Sangcha he records Naticopsis khurensis, Bellerophon sp. ind. aff. polito Waagen, and Pleurotomaria (Mourlonia) hunica. The two former seem to have no closely related species in the Guadalupian, but with the third Pleurotomaria euglyphea of the Delaware Mountain fauna may be compared. From the Lissar Valley Diener obtained a species of Pleurotomaria allied to P. punjabica, an undetermined species of Naticopsis, and an undetermined species of Bellerophon. The Naticopsis and Pleurotomaria seem to have related species in the Guadalupian, but this is less true in the case of the Bellerophon. From Byans only an undetermined species of Pleurotomaria is cited.

Among the fossils which Romanowsky described from Turkestan are a few Carboniferous gasteropods representing the genera Bellerophon, Porcellia, Euomphalus, and Pleurotomaria. For the most part these have themselves but little to do with any known Guadalupian species and are associated with different and apparently older faunas. In the case of Euomphalus pentangulatus there is at least some resemblance shown to the species which I have described as E. sulcifer var. angulatus.

In the Chinese fauna from Lo Ping the gasteropods appear to be surprisingly scarce. Kayser cites but a single species (Macrocheilus cf. angulifer White), with the possible exception of another identified as Nautilus or Warthia. The former probably has no allied Guadalupian form, but the latter may prove, when generically determined, to be correlated with the Guadalupian Warthia.

Loczy cites from the vicinity of Kantschoufu six gasteropods as Bellerophon? (Bucania) incertus, Bellerophon (Tropidocyclus) sp. indet., Bellerophon (Euphemus) cf. urei, Straparollus cf. placidus, Loxonema szechenyii, and Macrochilina kreitneri. Tropidocyclus sp. indet., Bellerophon cf. urei, and Straparollus cf. placidus appear to have no related species in the Guadalupian, but the three others at least show some superficial resemblance to the Guadalupian species of Bucanopsis, Loxonema, and Macrocheilina. From the Lantsankiang Valley this author cites an undetermined species of Pleurotomaria whose relation to Guadalupian types of the genus can not be determined.

Contrasting with the rarity of this group in the Chinese faunas is its representation in that from Padang as described by Fliegel. This author found no less than 25 species, which he refers to the genera Patella (1 species), Bellerophon (5 species), Euomphalus (2 species), Pleurotomaria (6 species), Murchisonia (1 species), Trochus (1 species), Naticopsis (5 species), Macrocheilus (3 species), and Loxonema (1 species). Patella anthracophila is probably only remotely related to the Guadalupian species of Patella, if at all. The same is true to a certain extent of the Bellerophons as well, though the species are either not figured or else are represented by molds. B. subcostatus is somewhat clearly unrelated, or remotely related, to anything in the Guadalupian. The two species of Euomphalus have also little to do with the two found in the Guadalupian. The Pleurotomarias figured by Fliegel represent rather large types and do not show any noteworthy relationship to those of the American fauna. The single species of Murchisonia from Padang is too imperfectly known to furnish the basis for an opinion. If it resembles any of the Guadalupian shells, it is more like some of those which I have referred to Pleurotomaria than those placed under Murchisonia. The form identified as Trochus? anthracophilus has no related form in the Guadalupian fauna, unless possibly among some of the species placed with Euconospira. Naticopsis subovata, and to a less extent N. sumatrensis, may be compared with the Guadalupian Naticopsis sp., but N. trautscholdi has no allied forms in our fauna. The other species of Naticopsis are not figured. N. elegantula, at least, seems, like N. trautscholdi, to be non-Guadalupian. Two of the species of Macrocheilus resemble the Guadalupian Macrocheilinas, but the third, Macrocheilus (Polyphemopsis) nitidulum Meek and Worthen, is, so far as known, non-Guadalupian. The single species of Loxonema also seems to have only a general relationship with the Guadalupian shells referred to Loxonema. The gasteropods of the Padang fauna are not presented in such a way as to make comparisons either easy or satisfactory, but they do not appear to show any essential relationship with those of the Guadalupe Mountains.

The same fauna had been previously described by Roemer, who identified 11 species of gasteropods, which he assigned to the genera Euomphalus, Pleurotomaria, Trochus, Macrocheilus, Murchisonia, Naticopsis, Patella, and Bellerophon. Euomphalus sumatrensis is only remotely related to either of the two Guadalupian species of the genus. Pleurotomaria orientalis is probably not closely allied to any of the Guadalupian Pleurotomarias. Trochus? anthracophilus reminds one also of a Euconospira, and if it should prove to belong to the Pleurotomariidæ may be compared to Euconospira obsoleta. Of the two species of Macrocheilus only one is figured. This is the form which Fliegel subsequently identified as Macrocheilus (Polyphemopsis) nitidulum M. and W. It resembles the Guadalupian species cited as Bulimorpha chrysalis var. delawarensis in some measure; but it is probably not a Bulimorpha, and is distinct from the Guadalupian Macrocheilinas. The single species of Murchisonia recorded by Roemer is likewise not figured. The two Sumatran species of Naticopsis are represented in the Guadalupian, but not closely, by Naticopsis sp. It appears to be nearer to Naticopsis brevispira. Roemer's Patella? anthracophila I can not but suspect is not a Patella but a brachiopod, a Crania, or possibly a discinoid. At all events it is quite unlike the Guadalupian Patella capitanensis. Bellerophon asiaticus is too imperfectly known to enter into a comparison of the Guadalupian with the Sumatran gasteropods, which whether viewed through the pages of Roemer's report or those of Fliegel's appear to have no essential relationship with the American fauna.

The only species of gasteropod mentioned by Rothpletz in his paper on the fauna of Timor and Rotti is compared by him to Straparollus permianus, a type which seems to have no related form in the Guadalupian fauna.

A considerable number of gasteropods enter into De Koninck's account of the Carboniferous faunas of New South Wales, only a moiety of them being from the upper ("Permo-Carboniferous") beds. The others it will not be necessary to consider. Platyceras altum and P. tenellum are found in the lower beds and possibly in the upper. Nothing resembling them has been discovered in the Guadalupe Mountains.

A number of species are placed with Pleurotomaria and Murchisonia. As might be expected, a general resemblance exists between this group and the Guadalupian Pleurotomarias, but nothing either sufficiently close as a whole or sufficiently marked in any particular to establish a relationship between the two faunas or any presumption of such. Euomphalus oculus and E. catillus are entirely unlike the Guadalupian species of Euomphalus. I find no trace of essential relationship between the two faunas in point of their gasteropod content.

Sixteen species of Gasteropoda are discriminated by Etheridge in the "Permo-Carboniferous" faunas of Queensland and New Guinea, referred to the following genera:

Etheridge's three species of Naticopsis are not figured (except a fragment of one of them), and in the Guadalupian also we have only imperfect specimens. Loxonema sp. appears to be related, though not closely, to the Guadalupian Loxonema swallowianum. Of Euomphalus the Queensland representation appears to have been very meager and, so far as I can make out, different from the Guadalupian species. Probably nothing as yet known in the Guadalupian can be compared with the two Australian species of Platyschisma, unless it be the imperfectly known form referred to Naticopsis. In configuration at least, Pleurotomaria carinata, as identified by Etheridge, resembles Pleurotomaria discoidea of the Guadalupian; but there is nothing in the Guadalupian which I would wish to compare with Etheridge's two species of Mourlonia. His figure of Mourlonia? coniformis is very bad, but represents perhaps a Euconospira. The poorly preserved Yvania konincki more or less resembles several Guadalupian types (perhaps Pleurotomaria richardsoni as much as any), but nothing very closely. Luciella? grayi is too imperfect and too poorly figured for the present comparisons. Murchisonia carinata probably is not closely allied to any Guadalupian form. Bellerophon stanvellensis, a type which recurs in so many faunas, is represented in the Guadalupian by Bellerophon crassus?. Bucania textilis is probably allied to the undetermined Guadalupian Bucanopsis; but to Porcellia pearsi I know of no corresponding Guadalupian form. On the whole I see but little real relationship between the Gasteropoda of the Guadalupian fauna and those described by Etheridge.

The gasteropods of the Moskovian are divided by Trautschold among the genera Cerithium, Pleurotomaria, Murchisonia, Euomphalus, Macrocheilus, Chemnitzia, Nerita, Natica, Capulus, and Bellerophon. As would naturally be expected, this fauna does not resemble that of the Guadalupian to any marked degree. The Moskovian species called Cerithium ignoratum by Trautschold is only remotely related to our Loxonema swallowianum. The identification of the two Pleurotomarias is queried, and neither species is figured. The only Murchisonia is likewise not figured. Of the two species of Euomphalus, one identified as E. tabulatus Phillips may be compared with one of the Guadalupian types. The single species of Macrocheilus is not similar to the corresponding Guadalupian Macrocheilinas. Nerita ampliata, which is not figured, and Natica omaliana probably have no Guadalupian representatives, unless in Naticopsis. The genus Capulus (or Platyceras) is not known in the Guadalupian, and the three Moskovian species seem to be without answering types. Only one of the four species of Bellerophon is figured, but that form, identified as B. costatus, is not closely related to the Guadalupian representatives of the genus. B. urei, another Moskovian species, belongs to a type which appears to be entirely lacking in our fauna.

Regarding the gasteropods of the Gschelstufe I have succeeded in procuring but a relatively small amount of data of a sort that could be used in the comparisons undertaken here. Stuckenberg cites 7 species of Pleurotomaria, 1 of Murchisonia, 1 of Bellerophon, 4 of Straparollus, 1 of Euomphalus, 1 of Capulus, 2 of Naticopsis, 1 of Loxonema, and 1 of Macrocheilus. While there are a number of pleurotomarioid types in the Guadalupian which are not represented among Stuckenberg's seven species, there are few of the latter which have not in the Guadalupian one or two species more or less closely related. The single representative of Murchisonia in Stuckenberg's fauna is less like the Guadalupian shells referred to that genus than certain of the Guadalupian Pleurotomarias, especially a poorly preserved form not mentioned specifically. Bellerophon hiulcus is not figured. Straparollus seems to be absent from the Guadalupian fauna. The single Gschelian Euomphalus is neither identified nor figured. Capulus is unknown in the Guadalupian, but Naticopsis sp. is more or less similar to one at least of the Gschelian forms and even shows a certain measure of resemblance to Stuckenberg's species of Straparollus and Capulus. The single Gschelian species of Loxonema is not at all like L. swallowianum, but the undetermined Macrocheilus from the Gschel very closely resembles Macrocheilina sp. a of the present report.

Nikitin's account of a Gschelian fauna comprises but a single gasteropod—Euomphalus canaliculatus—which is not closely related to either of the Guadalupian species. A few other generic types are recorded in lists, and one of these (Omphalotrochus) is important, since it seems to be sufficiently characteristic of one of the zones of the Gschelian to give a name to it. Omphalotrochus is not known in the Guadalupian fauna, but types, if not congeneric at least closely related, form a striking feature of one of the faunal zones of the underlying Hueco formation.

In his account of the Artinskian fauna Stuckenberg cites 28 species of gasteropods, belonging to the genera Patella, Pleurotomaria, Murchisonia, Bellerophon, Straparollus, Capulus, Natica, Naticopsis, Loxonema, Macrocheilus, Turbo, and Vermetus. Stuckenberg's Patella artiensis rather suggests to me a Crania; at all events it is not related to the Guadalupian Patella. The three which are figured of the five Pleurotomarias present no marked departure from Guadalupian types. The single species of Murchisonia, the five species of Bellerophon, and the single species of Straparollus are not figured. The only Guadalupian representative of the Gschelian Natica and Naticopsis appears to be Naticopsis sp., which is more similar in a general way to Natica cf. minima than to any of the others. Only two of the four species of Loxonema are figured, and they present no close relationship with L. swallowianum. Indeed, I am somewhat doubtful of the correctness of the assignment to this genus of Loxonema conicum. The figures rather suggest a Pseudomelania not unlike the Guadalupian species, or a Polyphemopsis. The single Artinskian species of Macrocheilus is rather closely related to Macrocheilina sp. a of the present work. The shell referred to Turbo obtusus Brown is not figured. Vermetus tschernyschewi represents a type at present unknown in the Guadalupian.

From the Kungurstufe, Stuckenberg cites 3 species of Pleurotomaria, 2 of Murchisonia, 2 of Bellerophon, 3 of Straparollus, 1 of Euomphalus, 1 of Natica, and 1 of Loxonema. The Pleurotomarias would scarcely appear alien if they were found in the Guadalupian fauna. Neither of the Murchisonias is figured, and the single cut representing one of the two species of Bellerophon tells very little. Straparollus is not known in the Guadalupian, and the three species cited by Stuckenberg are unfigured. Euomphalus sp. has little to do with the Guadalupian representatives of the genus, so far as one can determine from the inferior illustrations; and, finally, Loxonema phillipsi is not figured.

Krotow described a rather extensive gasteropod fauna from the sandstones of the Artinsk, but unfortunately his text is in Russian and his citations for the most part unaccompanied by figures. His list embraces the following species:

Of the six species of Natica three are figured, but none of them exhibits any but a very slight relationship with Naticopsis sp., which must be regarded as the corresponding Guadalupian genus. The species of Capulus are all unfigured, but as the genus has not been recognized in our fauna, they are probably to be reckoned among the non-Guadalupian forms. Oniy two of the Loxonemas are figured. One of them is related to L. swallowianum, though remotely. The other, of an altogether different type, is marked with spiral liræ and would probably more correctly be placed with Orthonema or some other genus than with Loxonema. We probably have nothing in the Guadalupian to compare with it.

Subulites sp. is not figured, nor is either of the two species of Macrocheilus. Actæonina sp. nov., however, is not very dissimilar to my Macrocheilina sp. a in general appearance. Both species of Turbo are without figures, but it may at least be said that the genus probably occurs in both faunas. All the species of Straparollus are unfigured, with the exception of S. variabilis. This form seems to be congeneric with the Guadalupian species of Euomphalus, but to be very different in its specific relations. The Bellerophons are unfigured, with the exception of three species. B. chaldinensis may be compared with Bucanopsis sp., and Bellerophon sphæroidalis and B. compressus certainly suggest Warthia americana, though no real relationship may exist. Some of the unfigured Bellerophons are non-Guadalupian, such as B. urei and others. Porcellia artiensis also has no corresponding form. The only figured species of Pleurotomaria are P. orientalis and P. dimorpha. Both in a general may resemble some of the Guadalupian Pleurotomarias. Of the two species of Murchisonia one is figured. It resembles neither the Murchisonias nor the Pleurotomarias of the Guadalupian. Only one of the two species of Patella is figured, and I suspect that it may possibly be a Crania. It has, at all events, nothing to do with Patella capitanensis.

In his account of the Permian fauna of the government of Kostroma Tschernyschew includes notices of only five gasteropods, most of which appear to have been in an imperfect condition. Chemnitzia volgensis and Straparollus permianus represent types which are apparently absent from the Guadalupian fauna. Some of the Guadalupian species referred to Pleurotomaria suggest Tschernyschew's Turbo? burtasorum in a general way, much more than does the Guadalupian form referred to the same genus. Bellerophon decussatus is probably non-Guadalupian, but Murchisonia subangulata is not unlike some of the Guadalupian Pleurotomarias, especially an unrecorded species, though possibly it is not related to the forms which I have here placed with Murchisonia.

Netschajew, however, found an abundant gasteropod fauna in eastern Russia, comprising no less than 44 species. Lepetopsis golowkinskyi appears to resemble the shell here described as Patella capitanensis, and they may prove to be congeneric also, as the interior of the Guadalupian species is not known. Seven species are referred to Pleurotomaria, but the Murchisonias, of which five species are recorded, also represent such types as I have included under that genus. While some of the Guadalupian Pleurotomarias belong to types not found in Netschajew's fauna, and some of his species, especially of Murchisonia, are types as yet unknown in the Guadalupian, the Permian Pleurotomarias and Murchisonias of Russia in a general way appear to resemble the Guadalupian Pleurotomarias very closely. Some of Netschajew's species of Turbo also resemble certain Guadalupian forms referred with more or less doubt to Pleurotomaria. Of the five species of Bellerophon two at least appear to be non-Guadalupian types (B. urei and B. piktorskyi), but B. elegans may be related to the imperfectly known species of Bucanopsis. As to the two remaining species nothing can be said, the figures being poor and the text in Russian. The genus Turbo, to which Netschajew refers six species, is represented in the Guadalupian by only one doubtfully determined species, which is much more closely related to T. burtasorum and T. angulatus than to the four other species. Straparollus permianus, Euomphalus pawlowi, and Naticopsis permica are types like which no Guadalupian species are known; but Natica minima suggests Naticopsis sp. of the present paper. Naticopsis sp. also resembles in some respects the form cited by Netschajew as Capulus permocarbonicus. This author refers twelve species to Loxonema, among which four different types, representing possibly as many different genera, can be discriminated. A few are of the normal Loxonema type, the whorls marked by strong longitudinal furrows. One of these resembles L. swallowianum. The majority of these Permian forms, however, appear to be entirely without sculpture, and such I would hardly approve of placing in the genus Loxonema. I have myself, however, provisionally placed in Loxonema a shell of this type which much resembles some of the Russian forms (e. g., L. phillipsi Howse). Another type (Loxonema sp.) is marked by revolving liræ and may prove to be an Orthonema, while still another (Loxonema ornamentarium) is ornamented with nodes and spiral lines. If the last two have any Guadalupian equivalents they will be found among the shells which I have placed with Pleurotomaria. Of the two Permian species of Macrocheilus, M. permicus appears to be closely related to Macrocheilina sp. a, M. globosus being as yet without a known equivalent. Subulites permianus also appears to be not remote from Bulimorpha chrysalis var. delawarensis.

Golowkinsky also includes some gasteropods in his paper on the Russian Permian fauna, citing six species. The single Bellerophon, an undetermined form, is too poor for comparison. Turbinella volgensis is probably non-Guadalupian, but Turbo burtasorum also, though its configuration is very suggestive of some of the Guadalupian Pleurotomarias, is probably to be compared only to Turbo? sp. of the Guadalupian, without apparently any close affinity. Pleurotomaria divesouralica is a type not found among the Guadalupian representatives of the genus, but Murchisonia subangulata is not unlike some of the Guadalupian Pleurotomarias. Emarginula? sp. suggests Patella capitanensis.

In conclusion I feel much hesitation at expressing a judgment regarding the relationship of the Guadalupian Gasteropoda with those of the Russian section. It appears to me neither very close nor very remote, greater perhaps with the Permian than with any of the other subdivisions.

In addition to the shells referred to above, Jakowlew has described an extensive series of gasteropods from the Donetz basin, including in fact over 50 species. The Bellerophons comprise but three species. Euphemus aff. nodocarinatus is, so far as known, a non-Guadalupian type. Bucania makatikhæ can be compared with Bucanopsis sp., but the other Bucania is unidentified and unfigured. Wortheniopsis claims five species, one of them unfigured. Of the others, three species rather strikingly resemble certain of the Guadalupian Pleurotomarias, such as P. richardsoni, P. arenaria, and P. delawarensis. The remaining one, W. netschajewi, has no closely allied species in my fauna. Two species are assigned to Rhaphistomella and these also are in a general way like species of Pleurotomaria in the Guadalupian. Pleurotomaria is employed for six species, one of them unfigured. P. antrina and P. kingi seem to be alien types to the Guadalupian fauna, but P. baranowkensis, P. præplatypleura, and P.? sibirtzewi are more like Guadalupian species. Rhineoderma nikitowkensis is possibly to be compared with Euconospira sp. of the present work. To Murchisonia Jakowlew assigns nine species. These types are somewhat less common in the Guadalupian than those with lower spire, and I also have referred them to Pleurotomaria. Probably the subgenus which he distinguishes as Glyphodeta is not represented among the Guadalupian forms, but the other types may find more or less closely related species there. Straparollus is represented by but one species and is a type not known in the Guadalupian, but Euomphalus includes three not especially like those of our fauna. Sosiolytes? vassilievkensis is non-Guadalupian and probably Turbonellina chatzepetovkensis, unless some of the doubtful Guadalupian Pleurotomarias prove to have that relationship. Portlockia rotundata and P. kamenkensis have a superficial resemblance to the form which I have called Pleurotomaria elderi, but they may be quite unrepresented in my fauna. Trachydomia wheeleri, Naticopsis kokeni, and Naticopsis tschernyschewi are non-Guadalupian. Tretospira, of which Jakowlew recognizes two species, has not yet been discriminated in the Guadalupian fauna. The Russian fossil identified as Loxonema peoriense may be compared with L. swallowianum. The other Russian Loxonema is unfigured.

Of the two species of Zygopleura that which is figured might be regarded as congeneric with the imperfectly known Loxonema swallowianum, though not closely related specifically. Macrocheilina intercalaris as identified by Jakowlew, though very much larger, appears to be closely allied to the Guadalupian Macrocheilina sp. b. Tuberculopleura, represented by five Russian species, is probably alien to the Guadalupian, as are also the single species of Omphaloptycha and the genus Promathildia, to which Jakowlew refers four species, though possibly some of the Guadalupian shells provisionally assigned to other genera may show a closer relationship when they are better understood. In fact Promathildia aff. kasanensis, P. biseriætuberculata, and P. anomala in a general way are suggestive, respectively, of the Guadalupian shells cited under Pleurotomaria sp. d, Pleurotomaria elderi, and Trochus? sp. The Guadalupian gasteropods are known in too little detail to make satisfactory comparison with those of the Donetz basin, where finer distinctions are drawn than it has seemed practicable to make among the indifferently preserved specimens from the Guadalupe Mountains, and I hesitate to place on record any expression of opinion on this point. While they undoubtedly have a number of features in common I can not feel that they are more than moderately allied.

The only gasteropod found by Abich among his fossils from Djoulfa was an undetermined species of Macrocheilus (Buccinum in the text). It is a much larger species than Macrocheilina sp. a, but is almost too imperfect to compare in other particulars. Arthaber when he reworked this fauna identified this form as Macrocheilus avellanoides De Koninck without figuring it.

A somewhat more extensive gasteropod fauna was found by Enderle in Asia Minor, six species being recognized. They are in every case characterized by relatively enormous size. It seems probable from Enderle's figures that Bellerophon attalicus is a Mogulia, or possibly a Warthia, but even in the latter event it is only remotely related to Warthia americana of the present fauna. Pleurotomaria? anatolica, if a Pleurotomaria at all, may be compared in a general way at least to some of the very much smaller species of the Guadalupian. Murchisonia stachei is probably non-Guadalupian. Murchisonia pergamena is more like some of the Guadalupian species, but Euomphalus sp. and Naticopsis arthaberi have no corresponding forms.

A very extensive gasteropod fauna was that described by Gemmellaro from the Fusulina limestone of Sicily. It comprises, in fact, no less than 79 species, or almost twice as many as are at present known from the Guadalupian. They are distributed among the following genera.

It is not known whether the Guadalupian shells agree in the essential or generic characters, but some of them are certainly very suggestive of Gemmellaro's genus Cylindritopsis. I refer especially to Macrocheilina sp. b and Bulimorpha chrysalis var. delawarensis, which resemble Cylindritopsis ovalis or C. inflata and C. conica, respectively. As to Gemmellaro's genus, it seems to me it should be compared more closely with Soleniscus and Bulimorpha.

The genus Loxonema shows a much greater differentiation in Gemmellaro's fauna than in the Guadalupian, and the specific representation is very different in each, the Sicilian forms comprising nothing comparable to L. swallowianum and very little which resembles L. inconspicuum. Gemmellaro's Strobeus elegans resembles no Guadalupian species so much as Bulimorpha chrysalis var. delawarensis. That species also closely resembles his Macrocheilus subulitoides. Gemmellaro has subdivided his Macrocheilus very closely, and most of his species more or less resemble either Macrocheilina sp. a or M. modesta. Macrocheilina sp. b, which has already been compared to his Cylindritopsis, seems to be out of this range. A few of his species, such as Macrocheilus barroisi, are fairly distinct from any known Guadalupian forms. The two forms referred to the genus Fossariopsis are probably non-Guadalupian, the only species which at all resemble them being pretty remote.

Gemmellaro has also made a close division of his species of Naticopsis. They naturally do not exhibit very wide limits of variation, and while none of them departs very far from the imperfectly known Guadalupian species, only one or two closely resemble it. Nerita palæomorpha is probably non-Guadalupian, and so are Nerita prisca and the three species of Platycheilus. Trochus adrianensis is very different from the doubtful Guadalupian Trochus and different from anything in the fauna. Sosiolytes also is non-Guadalupian, as are the three species of Chrysostoma. Turbinilopsis planorbiformis and Portlockia decorata are not figured in my copy of Gemmellaro's work. The two species of Turbonellina are not related to any of the known Guadalupian species, and Trachyspira, with its three species, is also quite alien to the Guadalupian fauna.

Among the Pleurotomarias Gemmellaro recognizes a large number of species, and having more perfect material than the Guadalupian rocks have yet furnished he was able to make finer discriminations of genera or subgenera than I have found practicable. Trochotoma, to which he assigns two species, appears to be unrepresented among the Guadalupian Pleurotomarias. Pleurotomaria discoidea most resembles the two Sicilian shells which Gemmellaro has placed with Temnotropis. Murchisonia sosiensis is probably more or less related to several of the Guadalupian forms. Gemmellaro's Pleurotomarias, including the subgenus Plocostoma, have really but little in common with the Guadalupian Pleurotomarias. There are not many striking forms in either fauna, but I remark in that from Sicily the absence of Euconospira or anything comparable to Pleurotomaria euglyphea, P. strigillata, and many others, and in the Guadalupian the absence of types resembling the Sicilian P. catherinæ and P. isomorpha, while of the less conspicuous types the generality are considerably different in both faunas. An instance of rather marked resemblance seems to be found in P. retroplicata of the Sicilian and P. richardsoni of the American fauna.

Gemmellaro divides his Bellerophons into Bellerophon, Waagenella, and Bucania. Most of his species are, unfortunately, not figured in the copy of his work to which I have access. The Bellerophons are probably more or less like B. crassus, but B. lamellosus is rather different from and B. cylindricus is altogether unlike any Guadalupian form. Bucania, in like manner, presumably corresponds to Bucanopsis, but B. sosiensis, the only Sicilian species whose figure has been seen, is considerably different from Bucanopsis sp. of the Guadalupian. Waagenella has not been recognized in the Guadalupian fauna, and, on the other hand, Warthia seems to be unknown in the other.

On the whole I find but little resemblance between the Guadalupian gasteropods and those of the Sicilian fauna from Sosio. The latter, as just pointed out, contains a number of groups which, so far as known, are absent from the Guadalupian. On the other hand, some of the Guadalupian types are absent from the Sicilian fauna. The most notable of these is Euomphalus; but I may also mention Patella, Euconospira, and Murchisonia (not the name but the corresponding type). Where the same types occur in both faunas the Sicilian shells are in several instances, of which Naticopsis is a good example, much more plentiful and highly differentiated. In the case of the Pleurotomarias, which are extraordinarily differentiated in both but proportionately much more in the Guadalupian, the general representation in each is largely peculiar and distinct from the other.

Schellwien, as is well known, treated only the brachiopods and Foraminifera in his reports on the faunas of the Carnic Alps. Gortani, however, discusses upward of 30 species from this region in a paper recently published. Unfortunately, many of the species identified by this author are not figured, and the figures of the others are very unsatisfactory. Since the fauna, so far as can be determined, has very little in common with that of the Guadalupe Mountains, I will not pause to consider it in detail, resting content with pointing out a few of the more general differences, such as the presence of Bellerophons of the type of B. de-angelisi, Mogulia? sp., and Euphemus (2 species), the predominance of the high-spired over the low-spired Pleurotomarias, the presence of Straparollus, Phymatifer, and Trachydomia, and the differentiation of Loxonema, 5 species being noted, several of which, in point of their slender, many-whorled shape, are comparable with L. swallowianum, though I have not satisfied myself that they have the same sculpture.

In his monograph on the Dyas, Geinitz distinguishes 17 species of gasteropods, which are distributed among the following genera: Paludina (1 species), Turbonilla (4 species), Turbo (4 species), Natica (1 species), Straparollus (1 species), Pleurotomaria (4 species), and Murchisonia (2 species). The shell identified as Paludina zwickaviensis is non-Guadalupian, but Turbonilla symmetrica suggests Macrocheilina modesta; T. phillipsi and T. altenburgensis suggest Loxonema inconspicuum; and Turbonilla roessleri is more or less closely related to Loxonema swallowianum. Turbo obtusus is non-Guadalupian, but the three remaining species of this genus possess a superficial resemblance at least to certain of the forms which I have seen more or less reason for referring to Pleurotomaria. They do not show much resemblance to Turbo? sp. Straparollus permianus seems to have no related Guadalupian form. Geinitz's Pleurotomarias and Murchisonias are in part not figured and in part poorly figured, but most of the six species included in these two genera appear to have types more or less closely related in the Guadalupian.

From the Permian of England, King cites 19 gasteropod types, referred to the genera Turbo (5 species), Rissoa (3 species), Loxonema (3 species), Macrocheilus (1 species), Euomphalus (1 species), Natica (2 species), Pleurotomaria (4 species). The five species of Turbo, with one exception (T. permianus), have among the Guadalupian Pleurotomarias species of the same general character which may possibly prove on better knowledge more closely related than might be inferred from the present generic assignment. Turbo mancuniensis is also related to Turbo? sp. of the present work. The three Rissoas are probably non-Guadalupian. Loxonema fasciatum, but more specifically Loxonema geinitzianum, suggests the Guadalupian Loxonema? inconspicuum, while the imperfectly known L. swedenborgianum is comparable in a general way to L. swallowianum. The English species of Macrocheilus, Euomphalus, and Natica, however, appear to be without any closely allied form. The Pleurotomarias of the English Permian, while much less varied, have a few analogous forms in the Guadalupian, but on the whole it seems to me that only a moderate degree of relationship can be traced between the gasteropods of the two faunas.

From the south point of Spitzbergen, Toula cites an unidentified species of Chemnitiza and a small Euomphalus, neither of which is figured. From the cape between the two arms of North Fjord he cites Pleurotomaria arctica and an undetermined Euomphalus. The Pleurotomaria resembles P. carinifera of the present paper. Lundgren cites Natica? sp. and De Koninck a species of Pleurotomaria which he identifies as P. verneuili. This group accordingly appears to be rather sparsely represented in this Arctic fauna and to show no special relationship to the Guadalupian gasteropods. A much more extensive series was described by Toula from Nova Zembla, amounting in all to 22 species. The genera Natica (1 species), Naticopsis (1 species), Chemnitzia (2 species), Loxonema (1 species), Euomphalus (1 species), Pleurotomaria (5 species), Murchisonia (2 species), Capulus (3 species), and Bellerophon (5 species) are recorded. Natica omaliana more or less resembles Naticopsis sp. of the Guadalupian, but probably the Naticopsis has no corresponding form. Chemnitzia hoferiana, which alone of this genus is figured, suggests Loxonema inconspicuum, but Loxonema brevis is only remotely related to L. swallowianum. The single Euomphalus is not allied to the Guadalupian representatives of the genus. Such of the Pleurotomarias and Murchisonias as are figured show only slight relationship with Guadalupian species. Two of the species referred to Capulus are non-Guadalupian. The third is unfigured, while the fourth to some extent resembles Naticopsis sp. Bellerophon hiulcus and B. decussatus probably correspond to B. crassus and Bucanopsis sp., but B. pulchellus of Toula still more suggests the latter species. B. carbonarius is an unknown type in the Guadalupian.

Among his fossils from the West Sahara, Stache found only 2 species of gasteropods, one identified as Pleurotomaria sp. and the other as ?Straparollus sp. cf. permianus King.

But few gasteropods are known from the Carboniferous of South America. Salter reported from Bolivia only a Euomphalus and a Euphemus, neither of which has allied forms in our fauna. From the same region D'Orbigny cited 5 species. Solarium antiquum and Euomphalus perversus are not especially close to the Guadalupian representatives of Euomphalus. Pleurotomaria angulosa is suggestive of P. discoidea, and Natica buccinoides and N. antisiensis are not closely related to the Guadalupian Naticopsis.

In the aggregate the American Pennsylvanian fauna shows a great diversity of gasteropod types, though as a rule in local collections they constitute one of the minor features. Rather in contrast to what was found in the Guadalupe Mountains, the Bellerophons are apt to be more common than the other gasteropods. In all, the Pennsylvanian fauna comprises over 150 species, distributed among 27 genera, but only a very few genera have 10 species or over. These are Bellerophon (including the groups Euphemus, Patellostium, etc.), Loxonema, Murchisonia, Pleurotomaria, and Soleniscus. On the other hand, 9 genera are represented by but a single species. All of these latter, together with some of the more extensively represented Pennsylvanian genera, are not known from the Guadalupe Mountains, but all those which in the typical Pennsylvanian areas are represented by numerous species occur also in the Guadalupian fauna. Among the more common Pennsylvanian types which are not known in the Guadalupian, mention may be made of Euphemus, Patellostium, Capulus, Orthonema (though some of the Guadalupian shells referred to other genera may belong there), Sph&aerlig;odomus, and Trachydomia. In view of the fact that only Patella (1 species), Warthia (1 species), Trochus? (1 species), and Pseudomelania (1 species), are peculiar to the Guadalupian in this relation, it can not so much be said that this fauna is generically different from the Pennsylvanian as that it is less highly differentiated.

Perhaps in the case of two faunas so closely situated geographically, faunal differences are to be looked for rather in the degree of species than in that of genera, and I find that in only one instance have I been able to cite a Pennsylvanian gasteropod from the Guadalupian fauna. Although the faunal difference is thus strongly marked, the peculiarity of the Guadalupian fauna appears to me less noteworthy in the case of its gasteropod representation than in the case of its brachiopods. Very few of the Guadalupian gasteropods if they should be found in the Pennsylvanian fauna would appear especially alien to it, whereas if this should happen with very many of the brachiopods they would almost immediately be recognized as strangers. This may, however, be due to the fact that brachiopods are so much more abundant and completely known that their measure in the standard Pennsylvanian faunas may be said to be pretty well taken.

A considerable number of gasteropods have been described from the western areas of the United States, but they are too scattered geographically and stratigraphically to constitute in any sense what may as yet be spoken of as a fauna. The Guadalupian forms are as different from these, so far as known, as from the Pennsylvanian species.

Family PATELLIDÆ Carpenter.

Genus PATELLA Linnæus.

PATELLA CAPITANENSIS n. sp.

Pl. VIII, figs. 5 to 5b.

The typical and only known representative of this species is a small specimen having an elliptical aperture and a generally conical shape. The altitude is rather high and the apex about central. Length 5 mm., width 4 mm., height 3.5 mm. The surface is cancellated by radiating and annular liræ, of which the latter are distinctly finer. The radiating liræ are sometimes alternating and are more closely arranged on the ends than on the sides of the shell. On the ends they are separated by intervals nearly equal to those between the annular liræ. On the sides the intervals are considerably greater.

The generic position of this shell is a matter of some uncertainty, for I suppose that it might be a Crania nearly as well as a gasteropod. The rather strong elevation, the centrally situated and erect beak, and to some extent the sculpture are rather more suggestive of the gasteropod than of the brachiopod type. It seems probable, therefore, that the genus to which it belongs is Patella or a type closely related to it.

Horizon and locality.—Top of Capitan formation, Capitan Peak, Guadalupe Mountains, Texas (station 2966).

Family PLEUROTOMARIIDÆ D'Orbigny.

Genus PLEUROTOMARIA Defrance.

Most of the Guadalupian shells referred to this genus are small, and to determine in them the presence of the characteristic slit band would require rather perfectly preserved material, so that the notch on the unbroken margin or the deflection of the growth lines could be made out. In the Guadalupian specimens these conditions are rather conspicuously lacking, since many of the forms are from the sandstone of the Delaware Mountain formation and are known only as molds of the interior, with which can be associated artificial impressions of the external mold. In many of the forms included under this title the presence of a slit band can be affirmed with some confidence, in others it is uncertain, and in still others it is rather doubtful. I suspect, therefore, that in addition to true representatives of the Pleurotomariidæ I may have included under this genus species which will subsequently find place among the Pyramidellidæ (or Pseudomelaniidæ), the Turbinidæ, the Trochonematidæ, or other families.

It may perhaps be asked why I did not withdraw the doubtful forms to the stations where my suspicions indicated that they should be placed. Several attempts to do so were in fact made, but in most cases it was possible to trace a connection, apparently a real connection, almost immediately into species in which the slit band was a fairly certain feature. It seemed best, therefore, to abandon such distinctions as I had sought to make, and to conclude that the data for a satisfactory or even a practicable treatment of these forms was not at hand. I would in fact have gladly relegated the investigation of them to another occasion furnished, let us hope, with more adequate material, but that course was not seriously to be contemplated.

The genus Pleurotomaria in its broad sense has of recent years been greatly subdivided into generic or subgeneric groups. The Guadalupian shells referred to Pleurotomaria present certain broad variations which enable their separation into groups of related species, but if serious difficulties existed in the way of assigning these forms to the genus Pleurotomaria the determination of their subgeneric relationship was a still harder task, and only in the case of the more easily recognized Euconospira has it been attempted.

The classification of the Guadalupian Pleurotomarias which has commended itself to me, though at present it is only provisional, is as follows:

Group of Pleurotomaria richardsoni.

Pleurotomaria richardsoni.

Group of Pleurotomaria carbonaria.

Pleurotomaria mica.
Pleurotomaria multilineata.
Pleurotomaria putilla.

Group of Pleurotomaria euglyphea.

Pleurotomaria euglyphea.
Pleurotomaria? sp. c.???

Group of Pleurotomaria discoidea.

Pleurotomaria discoidea.

Group of Pleurotomaria strigillata.

Pleurotomaria strigillata.
Pleurotomaria texana.
Pleurotomaria sp. d.
Pleurotomaria neglecta.
Incertæ sedis.

Group of Pleurotomaria? arenaria.

Pleurotomaria? arenaria.
Pleurotomaria? arenaria var. monolifera.
Pleurotomaria? planulata.
Pleurotomaria? cf. P.? planulata.

Group of Pleurotomaria? delawarensis.

Pleurotomaria? delawarensis.

Group of Pleurotomaria? carinifera.

Pleurotomaria? carinifera.
Pleurotomaria? carinifera var.

Group of Pleurotomaria? elderi.

Pleurotomaria? elderi.

It is the last four groups especially whose relationship to the Pleurotomariidæ is in doubt.

PLEUROTOMARIA RICHARDSONI n. sp.

Pl. VIII, figs. 9 and 9a.

This species consists of about four volutions. The spire is rather low, the body whorl occupying nearly two-thirds of the height. The exterior of the peritreme is divisible into three zones, on the basis of sculpture. The most prominent portion is a broad carina situated slightly above the peripheral line, on which was located the slit band. It is strongly elevated, defined above and below by distinct channels, the one beneath being somewhat the larger, and indented by a gentle sulcus. The two rims of the carina make sharp revolving liræ. The space between the channel which forms the upper limit of the carina, and the suture of the preceding volution, is convex and occupied by a row of large circular nodes, which are, however, lacking on the final portion of the body chamber. Below the carina the peritreme is also convex and is marked as far as visible by strong rounded liræ, about nine in number, separated by deep rounded sulci of approximately the same width. The volutions are embracing to the extent of concealing all of the revolving liræ except the uppermost—that which is just below the carina.

Height of typical specimen 6-1/2 mm; diameter slightly less than 5 mm.

This seems to be one of the commoner gasteropods of the Capitan limestone, for although it did not occur in our earlier collections a small lot obtained by Mr. Richardson at a later date contained four or five specimens. It is closely allied to Pleurotomaria subsinuata Meek and Worthen of the Pennsylvanian. It is a much smaller form and differs in at least one detail rather markedly, since just below the suture it carries a single row of large nodes, while the Pennsylvanian form is represented as having a double row of small ones.

Horizon and locality.—Top of Capitan formation, Capitan Peak, Guadalupe Mountains, Texas (station 2966). Delaware Mountain formation, southern Delaware Mountains, Texas (station 2964?). Delaware Mountain formation, Comanche Canyon, Glass Mountains, Texas (station 3763 ?).

PLEUROTOMARIA MICA n. sp.

Pl. VIII, figs. 12 to 12c.

This species is represented in our collection by a single specimen. Its size is extremely small, since it has a transverse diameter of but 3.5 mm., but the number of volutions (three) and the well-developed surface ornamentation indicate that it is nearly if not quite mature. The spire is low and the umbilicus probably partly closed. The band is concave and rather narrow. It is situated above the middle of the peritreme, perhaps one-third the way down from the suture. It is crossed by coarse transverse crenulations (?). Above and below the band the surface is traversed by fine, coarsely arranged, revolving liræ. The peritreme section is nearly circular, and each volution embraces the preceding one nearly up to the slit band.

This species belongs to the carbonaria group, and its nearest ally in the present fauna is Pleurotomaria multilineata. I am unwilling to refer it to that species, however, because the peritreme section is more nearly circular, the spire lower, the size much smaller, and the band crenulated. In shape it much resembles P. beckwithana, but the spire is lower and the band situated above the median line and crenulated. Of all the species known to me the lower Carboniferous P. subglobosa presents perhaps the closest resemblance. It has a lower spire and probably shows other differences which the figures alone of Hall's species do not permit me to distinguish.

Horizon and locality.—Middle of Capitan formation, Capitan Peak, Guadalupe Mountains, Texas (station 2926).

PLEUROTOMARIA MULTILINEATA n. sp.

Pl. XXIII, figs. 25 to 25d.

Shell rather small. Spire low, consisting of four or five volutions. Umbilicus small, partly closed. Peritreme section generally transversely elliptical, somewhat flattened on the upper exterior side and concave on the upper interior side. The flattening produces a sort of angulation, beneath which is a shallow sulcus. This occupies a nearly median position and is apparently the slit band.

The surface is marked by a large number of fine revolving liræ. These are thin and sharp, with interspaces wider than the liræ themselves. One or two slender revolving lines can be seen on the slit band also. There are about seven above the slit band, and probably not less than 15 or 20 below it. They become much finer toward the umbilicus.

This species apparently belongs to the group which includes Pleurotomaria broadheadi, P. beckwithana, P. carbonaria, P. newportensis, and perhaps other American Pennsylvanian species; but it seems to be distinct from any yet described. P. broadheadi, P. carbonaria, and P. newportensis are larger species, and all have a higher spire, a somewhat differently shaped peritreme section, and more or less different ornamentation. As a rule the band is farther from the suture, and has many more liræ intervening.

Horizon and locality.—Delaware Mountain formation, Guadalupe Point, Guadalupe Mountains, Texas (station 2931).

PLEUROTOMARIA PUTILLA n. sp.

Pl. VIII, figs. 11 to 11b.

Shell very small. Spire high, consisting of five or six volutions. Umbilicus probably closed. Peritreme section nearly circular. Strongly concave on the upper inner side by reason of adjustment to the preceding volution; gently concave about halfway between the outer median line and the suture. Convex above and below. Surface marked by moderately distant, sharp, revolving lines. These do not become appreciably finer in the umbilical region, but are fainter and perhaps finer in the depressed portion of the peritreme above the peripheral line. I am not sure that this form possessed a slit band, but if so its position was probably in this region. I have observed nothing in the revolving liræ elsewhere that indicates that the spaces between them served this function.

This description was drawn up from the typical specimen, which was obtained near the middle of the Capitan limestone. An additional example has come to hand from the southern Delawares. If really belonging to different species these two specimens, in spite of certain minor differences, are so closely similar that a specific separation would under the existing evidence be quite unjustifiable. The position of the slit band, which is obscure in the typical specimen, is clearly shown in the other. It consists of a sulcus, rather large for the size of the specimen, situated well up from the peripheral line, not far below the suture. A gentle concavity and the absence of revolving liræ have been noticed in the typical specimen at about this position.

Of the species recognized in this report Pleurotomaria? strigillata is in general appearance one of the closest to the present form. The mere difference in size would appear in this case sufficiently great to be of importance, and this is further augmented by such differences as the position of the slit band above the peripheral line. The persistence in arrangement and size of the striæ of the smaller form seems also to mark a difference. This shell is probably a Pleurotomaria of the carbonaria type, but it is so similar to Cyclonema leavenworthanum of the St. Louis group of Hall that where the slit band is obscured it might almost be taken for the same species. I know of no upper Carboniferous form which calls for serious comparison.

Horizon and locality.—Middle of Capitan formation, Capitan Peak, Guadalupe Mountains, Texas (station 2926). Delaware Mountain formation, southern Delaware Mountains, Texas (station 2935 ?).

PLEUROTOMARIA EUGLYPHEA n. sp.

Pl. XXIII, figs. 22 to 23b.

Shell rather large. Spire low, consisting of five or six volutions. Umbilicus large, open. Peritreme section transversely oval; somewhat concave on the upper inner side. There is a median concave band whose position is peripheral. It is bounded above by a heavy, flat-topped revolving ridge, just above which, separated by a shallow depression, is a revolving line. The lower margin of the band is formed by an elevation which enters below into the regular curvature of the peritreme. The surface above the slit band is marked by more or less regular, transverse, angular folds, which are slightly convex and strongly inclined backward. Below the band the surface is marked by fine, somewhat crowded, revolving liræ and by equally fine transverse liræ, which appear to pass upward onto the band, and possibly also onto the ridge above it.

So far as I have been able to ascertain, this species has no closely allied forms in the upper Carboniferous of the United States. Perhaps the species most suggestive of it is Pleurotomaria swallowiana of the St. Louis group of Hall, but the resemblance is too slight and the difference of horizon too wide to occasion any possibility of their being confused. P. valvatiformis of the "Lower Coal Measures" also remotely suggests it, but the resemblance is slight, the Guadalupian form seeming in fact to be a nearly unique type.

Horizon and locality.—Delaware Mountain formation, Guadalupe Point, Guadalupe Mountains, Texas (station 2931).

PLEUROTOMARIA? sp. c.

This division is established for a small shell from the Capitan limestone preserved as an internal mold. The general shape is discoid. The diameter is 7 mm. and the height about 4 mm. The spire, which consists of four volutions, rises gradually about as in Pleurotomaria euglyphea, or a little less rapidly. The umbilicus appears to have been large and open. The peritreme section approaches the circular, but is wider than it is high. It is concave on its upper portion just inside the suture, owing to apposition with the preceding volution. The upper part of the peritreme exterior to the suture in mature volutions is flattened and inclined downward. The peripheral portion is also slightly flattened, its direction being nearly parallel with the axis, though slightly inclined away from it. The under portion, which is likewise somewhat flattened, slopes gradually upward to the axis. The specimen, which seems to be preserved as an internal mold, retains no striæ or other surface ornamentation and has no marked angulation. The flattened areas merge into one another, so that the peritreme seems at first sight to be round, and the specimen is suggestive of a small Straparollus, such as S. quadrivolvis of the St. Louis group of Hall. The rise of the spire, however, is distinctly greater than it is said to be in S. quadrivolvis.

Since all the upper Carboniferous euomphaloids known to me are complanate, it seems rather more probable that the present specimen was a Pleurotomaria, to which supposition the shape of the peritreme is not unfavorable, although no slit band can be seen in its present preservation. It may possibly be an Omphalotrochus.

Horizon and locality.—Base of Capitan formation, hill southwest of Guadalupe Point, Guadalupe Mountains, Texas (station 2906).

PLEUROTOMARIA DISCOIDEA n. sp.

Pl. VIII, figs. 13 to 13d.

Shell small. Spire low, consisting of three or four volutions. Umbilicus probably small and partly closed. Peritreme section transversely elliptical, somewhat pointed at either end. In the older portion of the peritreme, however, there is a tendency for the outer end to become inflated, broader than the interior, and with a flattened periphery. The inner superior surface is gently concave. The outer superior surface is gently convex near the suture and gently concave below. There is a median carina, which appears to bear a row of nodes. Below the carina the curvature is broad and regular to the subangular inner margin, but its lower limit is fixed by a rather narrow sulcus, which probably carries the slit band. The surface above the carina appears to have been fairly smooth. That below it, including the sulcus, is marked by somewhat indistinct closely arranged revolving lines.

I know of no species with which this can profitably be compared.

Horizon and locality.—Middle of Capitan formation, Capitan Peak, Guadalupe Mountains, Texas (station 2926).

PLEUROTOMARIA STRIGILLATA n. sp.

Pl. XXIV, figs. 21 and 21a.

Shell of medium size. Spire high, consisting of six or seven volutions. Umbilicus small (?). Peritreme section concave on the inner superior side; otherwise nearly circular.

Surface marked by rounded revolving channels separated by sharp and slender ridges. The median channel is larger than the others, and along its center runs a sharply elevated line. Below the median one occur about thirteen others, which become increasingly narrow toward the umbilicus. The sculpture of the upper part of the peritreme to the suture seems to consist of three rather large channels, with thin, sharp intervening ridges. The lowest of these, that just above the median channel, probably represents the slit band, for here the growth lines are stronger than over the rest of the surface and have a concave or reentrant direction. Elsewhere they are faint and transverse or convex. Just below the suture there was developed a row of elongated nodes. There are traces of these on the typical specimen, which is defaced at this point, and they form a prominent feature of other associated specimens probably belonging to the same species.

Like some other Guadalupian types, this has species in the American upper Carboniferous allied to it, but I have found none with which it can with propriety be identified. Among the similar forms may be mentioned Pleurotomaria giffordi, P. humerosa, and P. subsinuata, of which P. humerosa is by far the nearest. P. humerosa shows, however, a lower spire and has the revolving ridges somewhat differently arranged.

Horizon and locality.—Delaware Mountain formation, Guadalupe Point (station 2931?); basal black limestone, Guadalupe Point (stations 2920 and 2967), Guadalupe Mountains, Texas.

PLEUROTOMARIA TEXANA n. sp.

Pl. XXIX, figs. 17 to 17c.

Shell small, consisting of about five volutions. Spire moderately high, approximately equal to the height of the body whorl. Umbilicus rather large and open. Peritreme section nearly circular and marked by a number of high, thin revolving liræ. The slit band apparently occupies a deep, broad sulcus, which traverses the peripheral line and is divided by a raised median lira, smaller in every way than those on the rest of the surface. Above the slit band and sulcus three of the liræ are found, and below, seven. The channels which divide the uppermost lira from the suture on one hand and from the second lira on the other are wider than those between others of the liræ.

Pleurotomaria texana recalls P. strigillata more than any other Guadalupian species, and is distinguished chiefly by the much lower elevation of the spire. It also recalls P. richardsoni in its general proportions, but the details of the sculpture are so distinct that it is hardly necessary to point out the differences. Among Pennsylvanian species, P. humerosa is probably the most closely related. P. texana differs from it in the arrangement of the liræ, which cover all the surface and of which one on the peripheral line is more or less atrophied.

Horizon and locality.—Delaware Mountain formation, southern Delaware Mountains, Texas (station 2969).

PLEUROTOMARIA NEGLECTA n. sp.

Pl. VIII, figs. 10 to 10c.

Shell small. Spire moderately high, consisting of about five volutions. Umbilicus probably closed. Peritreme section nearly circular, except for deformation resulting from apposition with the preceding volution. Surface marked by revolving sulci, separated by angular liræ. One of the former, distinctly wider and deeper than the others, occurs just below the peripheral line, and probably represents the slit band. Below the slit band are five or six relatively coarse revolving liræ, and above it about the same number of finer, less distinct ones.

This species is manifestly related to Pleurotomaria strigillata, and I hesitated considerably about separating them. In view, however, of the widely different horizons which they hold, and certain differences which appear to exist between them, it did not seem desirable to group both under one specific name. Shells of the present species having the same number of volutions are much smaller than P. strigillata, and the spire is perhaps a little more depressed. The slit band is slightly lower, and is not divided by a median line. The striæ above and below the band are relatively more heavy. The ornamentation of the smaller form, however, is very fine, and, especially above the band, is not clearly shown by my specimens. While it is possible that a complete knowledge would do away with some of the differences noted, I believe it would indicate still others and establish a specific distinction.

This form also resembles Pleurotomaria putilla, but it is much larger, has a somewhat more rapidly expanding spire, a distinct slit band, and relatively much coarser revolving liræ.

Horizon and locality.—Middle of Capitan formation, Capitan Peak, Guadalupe Mountains, Texas (station 2926).

PLEUROTOMARIA sp. d.

Shell rather small. Spire high, consisting of about five volutions. The peritreme section is in general nearly circular, but is concave on the upper portion inside the suture conforming to the previous volution. There is a broad, well-defined, flattened or more or less concave revolving band, whose center is on or perhaps a little below the peripheral line and whose direction is nearly parallel to the axis. This is probably the characteristic slit band. The distance between the upper limit of this zone and the suture is nearly twice as great as the width of the zone itself and the shell there is distinctly flattened. Each whorl embraces the preceding one so far that the width of the peripheral band is greater than the distance between its lower edge and the suture of the embracing volution. This lower portion also may be flattened or slightly concave. The whole surface is marked by sharp, slender, rather distant revolving lines. Two prominent ones, close together, on the upper margin of the peripheral zone may contain between them the slit band.

This form in some ways resembles Pleurotomaria multilineata, but is much more tapering. It has some points in common with P.? arenaria.. It is more tapering than that species also, and has a much more nearly circular peritreme section. The closest species, however, is P. delawarensis. The only prominent difference is that the present form has not a revolving groove below the broad vertical band.

Horizon and locality.—Delaware Mountain formation, Guadalupe Point, Guadalupe Mountains, Texas (station 2931).

PLEUROTOMARIA? ARENARIA n. sp.

Pl. XXIII, figs. 26 and 26a.

Shell of medium size. Spire rather high. Umbilicus probably small, possibly deep. Peritreme section approaching the hexagonal. Upper exterior face gently concave, sloping downward. Lateral face gently concave, parallel to the axis. Upper interior surface concave, sloping downward. The remainder of the perimeter is completed by a semicircular curve. The external suture is at or a little below the lower limit of the vertical or lateral face, the lateral outline of the spire showing a series of steplike descents, the upper surfaces sloping downward and the angles well marked. The junction of the upper and lateral faces on the exterior is marked by a fairly prominent carina, and another carina less strong and less persistent marks the junction of the lateral and lower faces.

The upper exterior face is crossed by sharply elevated, threadlike revolving liræ, of which there were about eight or ten. Those near the suture are stronger and more distant from one another than the lower ones, and are strongly nodulose, the corresponding nodes on adjacent liræ sometimes being connected, so that prominent though short-lived ribs are formed extending downward from the suture. The lateral face carries about four revolving liræ, with apparently a low lira midway between each two more elevated ones, and the lower surface was probably traversed with rather coarse revolving lines.

This species is found in moderate abundance in the sandstones of the Delaware Mountain formation, from which the typical specimen was derived. A similar form occurs also in the black limestone beneath, but it appears to be a distinct variety.

Pleurotomaria? arenaria shows some points of resemblance with P. brazosensis, P. marcouiana, P. grayvillensis, and P. subconstricta, but I have not been able to find among the described American species any one with which it can be identified. It possibly belongs to the group of Pleurotomarias for which the term Phanerotrema has been proposed; but the height and irregular outline of the spire are rather foreign to that genus. Further than this its generic position is uncertain.

This species appears to be closely related to Pleurotomaria strigillata of the underlying black limestone, and it is not always easy to distinguish specimens, which are usually presented in the form of molds. The two forms are, however, believed to be distinct. The present form is more strongly carinate and has fainter and finer revolving liræ and less distinct transverse ribs descending from the suture. By analogy with P. strigillata the slit band, if present, is situated not on the principal carina, but just above it.

Horizon and locality.—Delaware Mountain formation, Guadalupe Point, Guadalupe Mountains, Texas (station 2931).

PLEUROTOMARIA? ARENARIA var. MONOLIFERA n. var.

This variety occurs in the same beds as Pleurotomaria strigillata, but though resembling it to some extent appears to be more nearly related to P.? arenaria. The revolving liræ are perhaps a little stronger, the elongated ends or short wrinkles which descend from the suture are apparently absent, while the upper carina is ornamented by a row of strong nodes or tubercles.

My material of this variety is hardly suitable for illustration, but apparently shows the characters mentioned so unmistakably that it has seemed best to discriminate it under a distinct varietal name. Analogizing P.? arenaria with P. strigillata I was led to conclude that the zone immediately above the upper carina was the most probable position for the slit band in the latter species. If the present variety is indeed closely related to P.? arenaria, the occurrence of the row of nodes on the carina is hardly compatible with the occurrence of the slit band also on that feature, and to a certain extent supports the belief that it follows along its upper margin.

Horizon and locality.—Basal black limestone, Guadalupe Point, Guadalupe Mountains, Texas (station 2920).

PLEUROTOMARIA? PLANULATA n. sp.

Pl. XXIII, figs. 27 to 27c.

Shell rather small. Umbilicus closed (?). Spire low, consisting of about three volutions. Peritreme section in the mature portion subtriangular. The upper surface is broad, flattened, and nearly horizontal. The lateral portion is gently convex, nearly parallel to the axis. Its junction with the upper surface is formed by an angulation, and a similar sudden change of direction accompanies its return to the axial line. The lower surface consists of an area which is nearly parallel to the upper surface, and one which toward the axis has a more rapid upward direction. The inner portion of the upper surface is somewhat impressed by the volution against which it lies.

The upper and the lower surfaces are marked by heavy, sharp, rather distant revolving ridges, of which six or seven occur on the upper and probably an equal or somewhat greater number on the lower. The lateral portion is traversed by two, possibly three, revolving sulci, of which the lowest is indistinct. By these it is divided into four (or possibly but three) large rounded liræ, inclusive, of course, of those which bound it above and below.

Of the Guadalupian species thus far discovered, this in a general way most resembles Pleurotomaria discoidea. It can readily be distinguished, however, by its different peritreme section (especially because it has a flattened peripheral portion), and its heavier revolving liræ, which have, moreover, a different arrangement. Its real relations are probably with P. arenaria, although its much lower spire gives it at first an altogether different appearance. I know of no Pennsylvanian species with which it is likely to be confused.

Horizon and locality.—Delaware Mountain formation, Guadalupe Point, Guadalupe Mountains, Texas (station 2931).

PLEUROTOMARIA cf. P. ? PLANULATA.

Under this title is included a small and imperfect specimen from the southern Delawares which in general appearance is very similar to Pleurotomaria planulata. The spire is a little more elevated and the angle between the upper and lateral surfaces less rounded. The chief distinction, however, is found in the fact that the specimen under consideration, which I see no warrant for calling an internal mold, is without revolving liræ. Traces of the liræ are distinct on the typical specimen, which is certainly an internal mold in sandstone. Were it not for the apparent lack of sculpture upon the present specimen it might be provisionally identified as P. planulata.

Horizon and locality.—Delaware Mountain formation, southern Delaware Mountains, Texas (station 2969).

PLEUROTOMARIA? DELAWARENSIS n. sp.

Pl. XXIII, figs. 28 to 30.

Shell small. Spire high, consisting of about six volutions. Umbilicus probably small. Peritreme section subpolygonal, with flattened peripheral surface. Slightly inflated just below the suture, then gently concave to the first angulation or carina. This is followed by a rather broad concave band, succeeded by a second carina. The second carina is followed by another, somewhat narrow concave band, then a third angulation, indistinct on its lower side, after which the convexity is regular to the upper interior surface, where it is strongly concave. The upper exterior portion slopes rapidly downward, the two sulci on the lateral surface being nearly parallel to the axis. The suture of each whorl with that which succeeds it, seems to fall on or a little below the line of the third carina. A little below the suture a strongly raised revolving line is found, and another just a little above the first carina. In each of the two lateral sulci one or two fine liræ appear to be developed, while a considerable number of similar ones appear on the lower portion. The slit band, if present, may have been situated just above the upper carina, between the latter and the revolving line which follows immediately above. This, however, is merely a surmise.

In many ways this form may be looked at as a lofty variety of Pleurotomaria? planulata, which is probably its nearest related Guadalupian species.

Pleurotomaria? delawarensis appears to have no very close allies in the American "Coal Measures," except perhaps among those species which can not be handled to advantage until they have been authoritatively figured.

Horizon and locality.—Delaware Mountain formation, Guadalupe Point, Guadalupe Mountains, Texas (station 2931).

PLEUROTOMARIA? CARINIFERA n. sp.

Pl. XXIII, figs. 24 to 24b.

Shell rather small. Spire moderately high, consisting of four volutions. Umbilicus probably small or closed. Peritreme section somewhat rhombic. There is a large, high carina situated slightly above the median line. Immediately above and below the carina lie broad, shallow sulci, the surface resuming its convex curvature toward the axis in both directions, so that both external surfaces have a sigmoid curve in cross section. The upper inner side is strongly concave and the remainder of the surface around to the sulcus below the carina nearly regularly curved. The surface, so far as known, is without revolving liræ.

This species is quite distinct from any of the other Guadalupian forms, nor can I find anything in the Carboniferous faunas of the Mississippi Valley with which it is necessary to make comparison. It seems to be nearest allied to Pleurotomaria discoidea, found in the Capitan limestone, but has a higher spire, a stronger carina, and a more gibbous peritreme section. It is also without revolving liræ.

Horizon and locality.—Delaware Mountain formation, Guadalupe Point, Guadalupe Mountains, Texas (station 2931).

PLEUROTOMARIA? CARINIFERA var.

Pl. XXIX, fig. 19.

This variety is represented by a single imperfect specimen apparently closely related to Pleurotomaria carinifera, but how near, or to what degree the differences are constant and important, it is impossible at present to determine. Like the typical specimen of P. carinifera, that under consideration is an internal mold, but while the other was a mold in sandstone the present one is a mold in limestone. The number of volutions and the elevation of the spire can not be determined, but the spire may have been a little more elevated than in the typical variety. The peritreme section in its essential particulars is the same in both, but in the present specimen the carina is much more angular and defined above and below by much fainter sulci. In fact the surface above the carina is nearly flat and but slightly sigmoidal. Below the carina there is a broad and very slight depression, separated by an extremely faint angulation from the regular convexity of the lower portion.

On an unexfoliated fragment of the shell near the suture line are preserved two widely spaced, narrow though very slightly elevated revolving liræ, and possibly other portions of the surface were similarly ornamented. While no revolving lines have been preserved on the single external mold of Pleurotomaria? carinifera thus far found, I am not altogether satisfied that they were entirely absent.

Horizon and locality.—Delaware Mountain formation, southern Delaware Mountains, Texas (station 2964).

PLEUROTOMARIA? ELDERI n. sp.

Pl. XXIX, fig. 18.

This type is represented by a single small individual which has a height along the axis of about 6 mm., though the rather large oblique aperture increases the total length appreciably. The spire is gradually tapering and the apical angle is about 45°. There are about seven volutions. The umbilicus is closed. The peritreme section is nearly circular. A revolving sulcus, broader than any others which traverse the surface, probably marks the position of the slit band. It is situated about on the median line. Above the sulcus, between it and the preceding suture, occur three rather prominent revolving liræ. These and the one which forms the lower limit of the sulcus made by the slit band are rather strongly and relatively coarsely nodose. The upper one is smaller than the others and relatively widely distant from them. The lower portion of the peritreme is marked by five or six revolving liræ, which probably diminish in size and prominence, leaving the lowest parts almost smooth.

This form appears to be distinct from any of the other Guadalupian species. It is possible that it does not possess the characteristic slit band of Pleurotomaria and that its relations may be with an altogether different genus. Pleurotomaria? elderi is somewhat on the general plan of the Pennsylvanian Murchisonias, but differs from any species known to me from the Pennsylvanian, whether belonging to that genus or not.

Horizon and locality.—Delaware Mountain formation, southern Delaware Mountains, Texas (station 2969).

Genus EUCONOSPIRA Ulrich.

EUCONOSPIRA OBSOLETA n. sp.

Pl. VIII, figs. 14 to 14b.

Shell large, spire low, consisting of four or five volutions, or possibly more. Umbilicus rather large. Peritreme rhombic in section. The upper external surface gently convex and sloping downward. The upper internal surface gently concave and sloping downward. The lower surface at first sloping downward and later resurgent. Slit band narrow, peripheral, distinct, not concealed by succeeding volutions, though the suture occurs immediately below.

Surface nearly smooth. Entirely without revolving lines, but having faint, regular, transverse liræ. These are rather coarse, though obscure on the upper surface, where they are gently convex and swung strongly backward from the suture. On the under side they are minute, regular, and resemble growth lines. Here also they are directed backward from the slit band, but are several times gently flexed.

While this species agrees in many of its characters with Euconospira, I doubt if it is correctly referred to that genus. Its general expression rather recalls a much earlier type—the genus Liospira. The absence of revolving striæ and the comparatively large umbilicus are distinctly alien to Euconospira. Nevertheless I feel hardly justified in referring this species to Liospira, which seems to have become extinct long before Carboniferous time, and its real affinities in the Pleurotomariidæ are still a matter of doubt.

Horizon and locality.—Middle of Capitan formation, Capitan Peak, Guadalupe Mountains, Texas (station 2926).

EUCONOSPIRA HALLIANA Shumard.

1859. Pleurotomaria Halliana. Shumard, Trans. Acad. Sci. St. Louis, vol. 1, p. 399 (date of volume, 1860).

White [Permian] limestone: Guadalupe Mountains.

Shell depressed, conical, tapering rapidly to the apex; spire short; spiral angle 90°; volutions five or six, convex, slightly depressed below the middle and gently expanding at base; last volution occupying more than half the total length, gibbous, its exterior edge sharply carinated, under surface flattened convex; umbilicus deep infundibuliform; form of aperture unknown.

The under surface of the body volution is marked with several sharp revolving, threadlike lines; other surface markings unknown.

Resembles in general form P. Verneuilii of Geinitz.

Dimensions.—Length, 0.35; width, 0.38.

Locality.—White limestone, Guadalupe Mountains.

This species, Shumard's description of which is quoted above, has not been recognized among the more recent collections from the Guadalupe Mountains, and is probably distinct from Euconospira sp. from the southern Delawares.

EUCONOSPIRA sp.

This species is represented by a single specimen having a somewhat broadly conical shape. The basal diameter is 5-1/2 mm., the height 4 mm. or a little over. The base is rather strongly concave. The sloping external side of each volution is gently convex, and consequently the suture is slightly depressed. The lateral surface of the peritreme is marked by seven moderately coarse, strong, revolving liræ. The same sort of sculpture appears to extend to the introverted basal portion. The position of the slit band has not been observed, but it probably lies on the angle between the basal and lateral areas of the peritreme.

Horizon and locality.—Delaware Mountain formation, southern Delaware Mountains, Texas (station 2935).

Genus MURCHISONIA D'Archiac et De Verneuil?.

Murchisonia is often employed to include the high-spired slit-bearing spiral gasteropods, just as the low-spired species are distinguished as Pleurotomaria in the broad sense. While to a certain extent convenient, this is hardly a satisfactory way to divide that extensively diversified group; and, furthermore, if restricted to its typical species Murchisonia represents a type which is very different from most of the forms referred to it and which, without having seen specimens, I would be disposed to doubt as belonging with Pleurotomaria at all.

The shells for which the name Murchisonia is here used are very different from typical Murchisonia, and my only excuse for employing that term for them is that they are different from the Guadalupian Pleurotomarias, that they are doubtfully slit-bearing, and that others have used Murchisonia in the same sense.

MURCHISONIA? sp. a.

Pl. XXIX, fig. 20.

Under this title are included two small specimens, the larger of which has a length of 8 mm. and a diameter below of a little over 2 mm. The shape is thus very slender and tapering and consists of about eight volutions. The most obvious feature is a very prominent rounded carina, which seems to occupy a median position on the outer periphery of the peritreme. Aside from this the lateral surface is much flattened and the volutions so closely joined that they appear to form a continuous elongated cone. Between the recurrences of the carina the surface is marked by fine liræ, of which there appear to be five or six. The umbilicus is closed. So far as I can make out from the material at hand, the lower half of each volution, which is rounded and of some height, is enveloped by the succeeding one as far as the carina.

This species resembles Murchisonia terebra probably more than any other American species, but is clearly distinct from it. There is no closely related form in the Pennsylvanian, so far as I am aware.

Horizon and locality.—Delaware Mountain formation, southern Delaware Mountains, Texas (station 2969).

MURCHISONIA? sp. b.

The material representing this form is very imperfect, and I can do no more than make a brief mention of it. In a general way it is similar to the foregoing, but is less gradually tapering. The height is 5 mm. and the diameter at the base is 2 mm. The volutions number four or five. There appears to be a well-marked carina, as in Murchisonia? sp. a; but the other characters of sculpture are unknown. Not only is the spire in the present form less elevated, but the lower portions of the whorls are more prolonged.

Horizon and locality.—Delaware Mountain formation, southern Delaware Mountains, Texas (station 2969).

Family BELLEROPHONTIDÆ McCoy.

Genus BELLEROPHON Montfort.

BELLEROPHON CRASSUS Meek and Worthen.

Pl. XXIX, fig. 16.

1860. Bellerophon crassus. Meek and Worthen, Proc. Philadelphia Acad. Nat. Sci., p. 458.

Lower "Coal Measures:" Pittsburg, St. Clair County, Ill.

1866. Bellerophon crassus. Meek and Worthen, Rept. Geol. Survey Illinois, vol. 2, p. 385, pl. 31, figs. 16a, 16b.

Lower "Coal Measures:" Pittsburg, St. Clair County, Ill.

1875. Bellerophon crassus. White, Rept. U. S. Geog. Survey W. 100th Mer., vol. 4, p. 157, pl. 12, fig. 1a. (Whole volume published in 1877.)

Carboniferous: Camp Cottonwood, near Spring Mountain, Nov.

1884. Bellerophon crassus. White, Thirteenth Rept. Geol. Survey Indiana, p. 157, pl. 33, figs. 1, 2.

Upper "Coal Measures:" Sullivan and Posey counties, Ind.

1886. Bellerophon crassus (var.)? Heilprin, Ann. Rept. Second Geol. Survey Pennsylvania for 1885, p. 457.

Upper "Coal Measures:" Mill Creek limestone, Wilkesbarre, Pa.

1886. Bellerophon crassus (var.)? Heilprin, Proc. and Coll. Wyoming Hist. and Geol. Soc., vol. 2, pt. 2, p. 277.

Upper "Coal Measures:" Mill Creek limestone, Wilkesbarre, Pa.

?1887. Bellerophon (cf. crassus). Herrick, Bull. Sci. Lab. Denison Univ., vol. 2, p. 20, pl. 5, fig. 6.

"Coal Measures:" Flint Ridge, Ohio.

1891. Bellerophon crassus. White, Bull. U. S. Geol. Survey No. 77, p. 26.

Permian: Military Crossing, Baylor County, Tex.

1895. Bellerophon crassus. Keyes, Rept. Missouri Geol. Survey, vol 5, p. 151, pl. 50, figs. 1a, 1b. (Date of imprint 1894.)

Upper "Coal Measures:" Kansas City and Lexington, Mo.

1896. Bellerophon crassus. Smith, Leland Stanford Junior Univ., Publ. Cont. Biol. Hopkins Seaside Lab., No. 9, p. 39.

Lower "Coal Measures:" Conway County, Ark.

1896. Bellophon crassus. Smith, Proc. Am. Phil. Soc., vol. 35, p. 249.

Lower "Coal Measures:" Conway County, Ark.

1897. Bellerophon crassus. Ulrich, Final Rept. Geol. Nat. Hist. Survey, Minnesota, vol. 3, pt. 2, p. 853.

"Coal Measures."

1899. Bellerophon crassus. Girty, Nineteenth Ann. Rept. U. S. Geol. Survey, pt. 3, p. 592.

1903. Belleophon crassus. Girty, Prof. Paper U. S. Geol. Survey No. 16, p. 468.

Hermosa and Rico formations: San Juan region, Colo.

Maroon formation: Crested Butte district, Colo.

Weber formation and Robinson limestone: Leadville district, Colo.

In spite of differences in the associated fauna so great as to establish an a priori probability that the form under consideration is distinct from that which is found in the Pennsylvanian of the Mississippi Valley, I do not feel justified from the evidence in hand in referring it to a different species. It is true, however, that Bellerophons of this type seem to possess few lines of differentiation and that we find species very closely similar to one another occurring at the widest geographical intervals and at very different horizons in the Carboniferous

In the case of the Guadalupian material our collections contain but three specimens, only one of which is in a fairly perfect state of preservation. The outer surface is very regularly arched and the aperture is almost exactly twice as wide as high, having an elliptical shape with broadly curved ends. The slit band is narrow, about 1 mm. wide or a little more, and considerably elevated and rounded. The surface is marked by rather strong, regularly arranged, sublamellose transverse liræ, which are slightly curved, with the convex side forward. They are nearly transverse and perpendicular to the slit band, only very slightly bending backward in its vicinity. In crossing the slit band they are as strongly elevated as on the lateral areas. About nine occur in a distance of 5 mm.

Bellerophon crassus is not a very rare species in the typical Pennsylvanian, but well-preserved specimens are seldom to be had, the ordinary method of occurrence being as internal molds. I have had but a limited number of specimens with which to compare the Guadalupian forms, but such as have been seen indicate a considerable range of variation, part of which is without much doubt a matter of maturity in the specimens. The shape seems to be fairly constant, though the external curvature is perhaps more broadly rounded in mature and more acutely arched in young individuals. In some specimens the transverse liræ are nearly perpendicular to the slit band; in others they are more oblique to it or make a deeper reentrant angle in the outline of the lip. The slit band is apt to be depressed, especially in older specimens, but it may be fairly elevated and rounded. It is sometimes nearly smooth and at others crossed by lamellæ equally with the sides.

The Guadalupian form, unless it develops similar variations, which I have no means of ascertaining, differs from certain forms of B. crassus in having the slit band more elevated and crossed by strong sublamellose liræ and in having the liræ and growth lines more directly transverse. From other specimens it presents no appreciable differences which I have been able to ascertain.

Horizon and locality.—Delaware Mountain formation, southern Delaware Mountains, Texas (stations 2935 and 2964).

Genus BUCANOPSIS Ulrich.

BUCANOPSIS sp.

Pl. XXIII, figs. 14 to 14b.

Bellerophons, belonging apparently to the genus Bucanopsis, are not rare in the Guadalupian fauna, but so far none has been obtained except in the Delaware Mountain formation. The fossils from this horizon, especially the gasteropods and pelecypods, are preserved as molds in such a manner that often, probably through compression, external sculpture is retained more or less clearly upon the internal mold. This is the condition of the Bellerophons under consideration. Their external characters are seldom, if ever, clearly shown upon the internal mold, however, and I find on examination that an inadequate number of external molds have been preserved to properly study this group. Nevertheless, two very distinct species have been discriminated, one of which, that at present under consideration, appears to belong to the genus Bucanopsis. It has a broad flattened dorsum and large open umbilici. The aperture flares but slightly and is indented above by a deep notch. The slit band is slightly elevated and rather broad. The surface is marked by very numerous fine revolving liræ, separated by intervals wider than themselves. No transverse decussating liræ have been observed, yet the revolving liræ have a nodose appearance and may, in fact, consist of rows of small elevations instead of continuous lines.

Horizon and locality.—Delaware Mountain formation, Guadalupe Point, Guadalupe Mountains, Texas (station 2931).

Genus WARTHIA Waagen.

WARTHIA AMERICANA n. sp.

Pl. XXIII, figs. 15 to 17b.

This species is a narrower form than the foregoing, and the larger specimens obtained are considerably smaller. In young examples, especially, the dorsum is pointed or helmet-shaped. The shell does not appear to have been much expanded at the sides, and the umbilici were probably closed. The aperture was strongly emarginate above, the reentrant angle terminating in a not very distinct notch.

The surface appears to have been devoid both of transverse and revolving liræ and of a slit band. No trace of sculpture or slit band can be found on either external or internal molds. Furthermore, a small silicified specimen from the southern Delawares, which probably belongs to the same species and without much doubt to the same genus, also presents only a smooth surface to the eye, without either liræ or band.

It seems very probable, therefore, in spite of the unsatisfactory preservation of my specimens, that we have here a form which departs widely from the type of Bellerophons common in our Pennsylvanian faunas. I think that it can with reasonable assurance be assigned to Waagen's genus Warthia. It seems to differ from Mogulia, which also is without a slit band, in having the outer lip with a deep angular notch and the surface smooth instead of crossed by heavy transverse bands.

Of the Indian Warthias the present species most resembles W. polita, but is still narrower. It is rather more closely allied to the form from New South Wales originally described as a Bellerophon, but subsequently placed by De Koninck under Goniatites because he could find no slit band. This species, Bellerophon micromphalus, will probably prove to be a Warthia. W. americana appears to have a relatively wider aperture and to be more expanded near the umbilici.

Mention has already been made of a small specimen from the southern Delawares which probably belongs with Warthia americana. It differs somewhat distinctly being more flaring at the sides in the umbilical region, but as probably all the specimens from Guadalupe Point are more or less broken, particularly on the most projecting portions, I am disposed to believe that the best of them more or less misrepresents the shape of the aperture. A relatively small amount broken from the shell as it projects near the umbilici would cause an appreciable difference in the outline.

Horizon and locality.—Delaware Mountain formation, Guadalupe Point, Guadalupe Mountains, Texas (station 2931). Delaware Mountain formation, southern Delaware Mountains, Texas (station 2969?).

Family EUOMPHALIDÆ De Koninck.

Genus EUOMPHALUS Sowerby.

EUOMPHALUS SULCIFER n. sp.

Pl. XVI, figs. 23 to 24a.

Shell rather small; nearly complanate, consisting of four or five volutions. Upper surface almost flat or slightly concave, lower surface moderately concave.

The upper surface of the peritreme is generally flat. Near the outer margin it is abruptly indented by a deep, narrow sulcus, the marginal portion of the upper surface forming a strong carina, which has, however, a nearly vertical direction. The suture is well defined. Peripherally the peritreme is flattened and inclined inward from the upper rim. It seems to bear in the older whorls a shallow indistinct depression. The under side is more convex than the upper and converges with it in the direction of the axis. The peripheral rim is somewhat angulated and just within the angulation runs a shallow groove. The under side of the peritreme therefore resembles the upper, but with characters less strongly marked. These modifications of the surface are, however, nearly all due to thickening of the shell, the internal sections being to all intent circular. The surface is also marked by rather strong transverse lines and toward the aperture by indistinct, more or less regular annulations.

I have assigned this species to Euomphalus, though it seems to display many transitional characters to the genus Discohelix.

Euomphalus sulcifer and the variety next to be described are quite different from any known Pennsylvanian representatives of the genus.

Horizon and locality.—"Dark limestone," Pine Spring (station 2930); basal black limestone, Guadalupe Point (station 2920), Guadalupe Mountains, Texas.

EUOMPHALUS SULCIFER var. ANGULATUS n. var.

Pl. XVI, figs. 25 and 25a.

This variety is distinguished from the shell figured on the same plate. It differs from the normal type by having the channel which traverses the upper surface of the peritreme expanded and bounded on its inner side by a sharp carina, the inner upper portion of the peritreme being concave. This channel also slopes downward so that the peripheral carina, instead of being vertical, is directed more nearly outward.

The variety angulatus has the appearance of being very distinct from Euomphalus sulcifer, to which at the same time it is obviously related. My series of specimens, being rather limited, does not permit me to determine how far the two types pass into one another, and I have described the second merely as a variety of the first.

There seems to be little danger of confusing these forms with any known species of Euomphalus or Straparollus. The only one known to me which resembles them at all closely is E. exortivus Dawson, from the Carboniferous limestone of Nova Scotia. Dawson's species is rather nearer the variety angulatus, but the wide difference in geologic age and the sharp angular carina of the Guadalupian form serve as adequate distinctions.

Horizon and locality.—"Dark limestone," Pine Spring, Guadalupe Mountains, Texas (station 2930).

Family TURBINIDÆ Adams.

Genus TURBO Linnæus.

TURBO GUADALUPENSIS Shumard.

1859. Turbo Guadalupensis. Shumard, Trans. Acad. Sci. St. Louis, vol. 1, p. 398 (date of volume, 1860).

Dark [Permian] limestone: Guadalupe Mountains.

Cast elongate ovate; spire conical, tapering more gradually to the apex than we usually find in species of this genus; spiral angle, 470; volutions four or five, moderately convex, last one slightly ventricose, longer than the spire; suture linear, distinct; aperture ovate (?); surface marked with numerous obscure, closely set, revolving lines, which are wider than the spaces between.

Dimensions.—Length, 0.85; width, 0.48.

The collection contains merely a single finely preserved cast of this species. In general form, it resembles some of the recent species of Linnæa.

Locality.—Dark limestone, Guadalupe Mountains.

The above is Shumard's description of this species, which appears not to have been obtained in the more recent Guadalupian collections.

TURBO? sp.

This type is represented by a single imperfect specimen having much the proportions and general appearance of Pleurotomaria richardsoni, but with somewhat different sculpture and apparently without a slit band. The body whorl occupies over half the entire height. The spire is rather low and the umbilicus closed. The outer half of the peritreme section may be compared to a similar portion of a regular hexagon. A deep channel traverses the median line, bounded above by a carina which for the size of the shell is strongly elevated and broadly rounded. The carina corresponds in position to the carina of Pleurotomaria richardsoni, but instead of being flattened on top and bearing the slit band, it is sharply rounded and marked by coarse and somewhat oblique crenulations. The carina is followed above by a strong sulcus, between which and the suture appears to be a raised band with vertically elongated nodes. A carina nearly equal to that above the median sulcus defines its lower limit, beneath which are about four strong liræ diminishing in size and prominence toward the axis. Part of the lower portion, and probably the whole, is crossed by moderately coarse, strong, sharply elevated, oblique liræ, probably continuous with the crenulations on the top of the carina.

This form, of which the principal characters, so far as shown by my not very perfect specimen, have been hastily sketched above, is clearly distinct from P. richardsoni, though much resembling it in a general way. It is possible, however, that it may be one of the Pleurotomarias, though this seems at present less probable.

Horizon and locality.—Delaware Mountain formation, southern Delaware Mountains, Texas (station 2969).

Family TROCHIDÆ Adams.

Genus TROCHUS Linnæus.

TROCHUS? sp.

From the white limestone of the Capitan formation has been obtained a single specimen, very imperfect, which at the same time differs strongly from any of the forms described from this horizon and yet is too imperfect to establish as new. The spire was high, but the approximate number of volutions can not be ascertained. The diameter of the largest whorl is 5 mm. and its height about 2.5 mm. The under side of the peritreme is flattened and slightly inclined downward from the axis, causing the lower side of the shell to be slightly concave. The lateral surface of the peritreme is distinguished from the basal by an acute angulation, and is itself slightly dihedral. The lower half is nearly flat, not quite parallel to the axis, but inclined toward it. The upper half is also nearly flat and inclined to the axis at an angle of about 45°. The union of the two surfaces is marked by a sharp revolving ridge, between which and the basal angulation another sharp ridge is found with an intermediate position. The lower half of the lateral surface of the peritreme, therefore, appears to be marked by three nearly equal revolving angular liræ.

No other surface ornamentation has been preserved besides the three ridges, and it is uncertain whether or not either of the two depressed bands between them functioned as a slit band. I am very doubtful about this species belonging to the Pleurotomarias, and it seems at present to be more nearly related to Trochus.

Horizon and locality.—Middle of Capitan formation, Capitan Peak, Guadalupe Mountains, Texas (station 2926).

Family NERITOPSIDÆ Fischer.

Genus NATICOPSIS McCoy.

NATICOPSIS sp.

Pl. XXIII, figs. 18 to 19b.

This form is represented in our collections by but two specimens, both from the Delaware Mountain formation. One of them is rather small, and as both are preserved as molds and the larger is distorted by pressure I feel that it would not be safe either to identify them with known species or to describe them as new, especially in a genus where the discrimination of species depends to so large a degree on configuration.

The general character can be seen by the illustrations, for the form is one of those in which few marked peculiarities exist. The size is rather small, the spire low, the peritreme rapidly enlarging, and the final volutions large and inflated.

This form seems to resemble Naticopsis dispassa Dawson, but the figure of that species given by its author is so wretched that only the general character can be ascertained from it. It also resembles another lower Carboniferous species, Naticopsis carleyana, but differs in having the body whorl broader and not so high. By a similar character it differs from Naticopsis nana, having a less inflated body whorl. Some of the other species of Strophostylus are of the same general type, but their much greater size renders it difficult to compare my fossil with them. I am uncertain whether this form is rightly a Naticopsis or a Strophostylus.

Horizon and locality.—Delaware Mountain formation, Guadalupe Point (station 2931); basal black limestone, Guadalupe Point (station 2967), Guadalupe Mountains, Texas.

Family PYRAMIDELLIDÆ Gray.

Genus ZYGOPLEURA Koken.

ZYGOPLEURA SWALLOWIANA Shumard.

1859. Chemnitzia Swalloviana. Shumard, Trans. Acad. Sci. St. Louis, vol. 1, p. 399 (date of volume, 1860).

White [Permian] limestone: Guadalupe Mountains.

Shell subulate, very gradually tapering to the apex; spinal angle 12°; volutions about 15 (?) very gently convex; suture well marked, excavated; surface of volutions ornamented with longitudinal, arched folds which do not cross the suture; aperture unknown.

The collection contains but a single specimen of this shell, which is imperfect.

Locality.—White limestone, Guadalupe Mountains.a

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aTrans. Acad. Sci. St. Louis, vol. 1, 1856-1860, p. 399.

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My material of this species is somewhat imperfect, and were it not that the form defined by Shumard, whose description is not very full, is characterized by the extremely large number of volutions, I would feel much doubt about referring my shells to it.

The larger of the two specimens at hand has a height of 13 mm. The diameter at the base is 4 mm. and at the top about 0.5 mm. The spire is thus seen to be very high and tapering. There are about 12 volutions existing, while several are clearly missing at the top. The suture lines are nearly horizontal. The peritreme section is about circular, the shape being little if at all modified in each volution by the apposition of those above and below. The diameter of the peritreme at the larger end is slightly in excess of 2 mm. The surface may have been smooth, or differently marked, but appears to have possessed rather narrow vertical corrugations, of which a considerable number occur on a single volution.

The smaller specimen has a height of but 7.5 mm., with a basal diameter of but 2 mm. The apex is produced nearly to a point, and there are about ten volutions. The surface of this specimen is not preserved.

The foregoing notes are taken from specimens which are preserved for the most part as internal molds. The sutures, therefore, appear much more deeply indented than it was probable was really the case. I believe, however, that the suture line was really distinctly depressed.

There can be little doubt that neither the shell described by Shumard nor that here subsumed under the name proposed by him, if they are not the same, is a Chemnitzia. They appear to be congeneric with or at least to resemble the group of upper Carboniferous species for which the name Loxonema is used.

Horizon and locality.—Middle of Capitan formation Capitan Peak, Guadalupe Mountains, Texas (station 2926).

Genus LOXONEMA Phillips.

LOXONEMA? INCONSPICUUM n. sp.

Pl. XXIV, fig. 19.

I have but a single specimen of this form, of which, on account of its small size and not very perfect preservation, a complete description can not be given. The size is small and the shape long and slender, the length being 3 mm. and the width of the lowest whorl 1 mm. or a little less. The volutions number six, or possibly seven. The convexity of the whorls is considerable. The peripheral line is situated from one suture about one-third the entire distance to the next below, and at this point the outline is in fact rather abruptly deflected. The suture is depressed.

The surface appears to be entirely smooth.

This species resembles Loxonema cerithiiforme, but the whorls are higher and less numerous, and there are no little nodes along the lines of suture. It is also related to L. peoriense, but is much smaller and with a larger apical angle.

Horizon and locality.—Basal black limestone, Guadalupe Point, Guadalupe Mountains, Texas (station 2967).

Genus PSEUDOMELANIA Pictet.

PSEUDOMELANIA sp. a.

This species is represented by a mere fragment, which it would scarcely be worthwhile to mention separately, except that it is rather exceptional in its characters. Of the two volutions preserved, one has a height of a little less than 5 mm., while that above it is a little over 3 mm. The whorls are without ornamentation, almost flat laterally. What may be discriminated as the lateral and lower portions are about equal in height and are distinguished by an angulation marking the limit to which each volution is enveloped by that which succeeds it. The suture is very slightly depressed. The larger diameter is about 5 mm. and the taper very gradual. The spire, therefore, must have been extremely high and in shape regularly conical, and the number of volutions was without doubt large. The body whorl appears to have been relatively small. The general appearance of these fragments is that of a Pseudomelania, a genus which is thought to extend back into the Carboniferous period.

This shell is quite unlike anything else in the collection, and I can recall no form resembling it among our Carboniferous faunas.

Horizon and locality.—Delaware Mountain formation, Guadalupe Point, Guadalupe Mountains, Texas (station 2931).

PSEUDOMELANIA? sp. b.

I include here only a single small, imperfect specimen which appears to possess the following characters:

The shape is very small and slender, with many volutions. Height about 6 mm., diameter below a little less than 2 mm. Volutions about nine in number. The peripheral surface of the volutions is so flattened and their line of union so ill defined that in my poorly preserved example they are individually indistinguishable. The lower part of the peritreme is nearly flat, so that the volutions are but very slightly embracing. In this respect, as in size, the present form is in distinct contrast to the foregoing one.

It very closely resembles in a general way the smaller of the two specimens identified as Loxonema swallowianum, but seems to have a much flatter lateral surface and somewhat less rounded basal portion. It also appears to be without the sculpture which is presumably a character of the small example of Loxonema. I am somewhat in doubt whether this may not be an imperfect example of the form cited as Murchisonia? sp. a.

Horizon and locality.—Delaware Mountain formation, southern Delaware Mountains, Texas (station 2969).

Genus BULIMORPHA Whitfield.

BULIMORPHA CHRYSALIS var. DELAWARENSIS n. var.

Pl. XXIII, fig. 21.

This variety, of which our collection contains but a single specimen, is in general form spindle-shaped, the moderately high spire consisting of five or possibly six volutions, and the body whorl occupying about half the whole length. In configuration it appears to be intermediate between Bulimorpha bulimiformis of the "Lower Carboniferous" and B. chrysalis of the "Upper Carboniferous". It seems to be a little less elongate than the Mississippian species, the spire especially being not quite so tapering. On the other hand, the body chamber is a little more inflated than in the Pennsylvanian form. The difference, however, is not large, and had the form under consideration been found in association with the usual fauna of the "Coal Measures" of the Mississippi Valley I would probably have neglected it.

Horizon and locality.—Delaware Mountain formation, Guadalupe Point, Guadalupe Mountains, Texas (station 2931).

Genus MACROCHEILINA Bayle?

The few imperfect shells included under this title are probably congeneric with those with which Phillips's term Macrocheilus is commonly associated. When Phillips introduced Macrocheilus in 1841, the name had already been anticipated by Macrocheilus Kirkby, 1838, proposed for a genus of insects. Long afterwards, in 1879, Bayle, on the strength of this fact, wished to replace Macrocheilus Phillips by the term Duncania, but finding that also preoccupied for a genus of corals, finally, in 1880, substituted Macrocheilina. While most authors have retained the more familiar name, I do not at present see how that course can be justified.

When first suggesting the term Macrocheilus, Phillips did not give a generic description, but only introduced it tentatively for some shells which had previously been included under Buccinum. The first species mentioned and the first species described in connection with Macrocheilus is M. brevis, which must probably be taken as the type.

Now, most of the Buccinidæ are highly ornamented species and Macrocheilus brevis has a row of large nodes near the suture, with apparently other nodes on the body whorl, presenting, in fact, an appearance very different from the Carboniferous shells which it is customary to refer to Macrocheilus. Bayle's Duncania was associated with Buccinites arculatus Schlotheim as the typical species, and in this case, also, no description was given. Macrocheilina was simply substituted for Duncania.a

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aJour. de Conch., ser. 3, vol. 20, p. 241.

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Buccinites arculatus is a large shell in Schlotheim's figure, with a shoulder just below the suture and a suggestion of nodes along it, in configuration considerably different from most of the shells from the American Carboniferous referred to Macrocheilus.

So far as I have investigated the subject, it seems to me that Macrocheilus must in any event yield place to Macrocheilina; but, on the other hand, it seems doubtful if more than a very few of the Carboniferous species of Macrocheilus can properly be retained under Macrocheilina. As, however, I am in no position to indicate the proper disposition of the shells which I would exclude from Macrocheilina, including, of course, the Guadalupian species at present under consideration, I have retained Bayle's name for them, but in a provisional manner.

The three species included under Macrocheilina in the present instance are imperfectly known, and it is not certain that they are congeneric with one another. Macrocheilina? modesta and Macrocheilina sp. a are more comparable to M. arculata, while Macrocheilina sp. b, with its low spire and large and deeply embracing whorls, appears to belong to at least a different group of species.

MACROCHEILINA? MODESTA n. sp.

Pl.XXIV, fig. 20.

Our collections contain only one specimen of this shell, which is of very small size and fusiform shape, rather rapidly enlarging. The length is slightly less than 3 mm. and the width below about half the length. The volutions number four to four and one-half. The whorls are moderately convex and the suture depressed.

The aperture is oval, longer than wide, and nearly parallel to the axis. The surface is smooth.

Horizon and locality.—Basal black limestone, Guadalupe Point, Guadalupe Mountains, Texas (station 2967).

MACROCHEILINA? sp. a.

Pl. XXIII, fig. 20.

Shell of medium size, consisting probably of seven or eight volutions. Spire moderately high, the body whorl comprising about half the entire length. The volutions are somewhat flattened, and the final one is rather elongated. The sutures are moderately depressed. It is uncertain whether this shell possessed the fold on the columella, which is one of the characters of Soleniscus, for the preservation is that of an internal mold and the aperture is complicated by crushing, but if this character was present it was probably strongly marked.

This species resembles several found in the "Coal Measures" of the Central and Eastern States, but the single specimen preserved in our collections is so imperfect that its relations to other forms can not be precisely ascertained. It is some what like S. altonensis, but the spire was probably higher and the body whorl not so large. S. fusiformis also resembles it, but probably has a higher spire. S. hallanus appears to be very similar indeed, and I would feel disposed to refer the Guadalupian shell to that species pending a fuller knowledge of its characters were it not that the entirely different faunal association in which it occurs would, a priori, afford evidence against its being the same species. S. humilis has a proportionately larger body whorl, though in general rather similar. S. newberryi is another closely related species. It probably has a higher spire, but this portion of my specimen being lost this character can only be surmised. S. paludiniformis is similar, but only in a general way, and as the Guadalupian form, all of whose characters are not known, occurs at a different horizon and is associated with a very different fauna the propriety of ignoring these differences is doubtful.

Horizon and locality.—Delaware Mountain formation, Guadalupe Point, Guadalupe Mountains, Texas (station 2931).

MACROCHEILINA? sp. b.

The only specimen representing this species is very small, with a large body whorl. The general shape of the whole is fusiform, regularly tapering at both ends. The entire height is only about 3 mm., of which the spire, consisting of three volutions, occupies only one-fifth. The width is a little less than 2 mm.

Horizon and locality.—Delaware Mountain formation, southern Delaware Mountains, Texas (station 2964).

CEPHALOPODA.

The Cephalopoda form an interesting and characteristic, often an abundant, feature of the later epochs of the Paleozoic. The small number which it has been possible to include in the present report has accordingly been somewhat of a disappointment. It seems probable, however, that this group may be even abundant at some horizons and some localities of the Guadalupian, for Mr. Richardson, limited as to time and conveyance, obtained a far more plentiful and varied representation than our party, with its more leisurely movements and its more primary purpose of making collections. It is a rather singular fact that none of the ammonoids, to which group the foregoing remarks chiefly apply, have as yet been found in the upper or Capitan formation of the Guadalupian. All the material thus far obtained is from the basal black limestone and from the Delaware Mountain formation of the Guadalupian section, and from corresponding beds in the southern Delawares.

Known Cephalopoda of the Guadalupian comprise only the following genera:

Among the Nautiloidea, Orthoceras (1 species), Foordoceras (2 species); among the Ammonoidea, Gastrioceras (2 species), Paraceltites (1 species), Agathoceras (1 species), Peritrochia (1 species), and Waagenoceras (1 species).

The Salt Range fauna has furnished, according to Waagen, 4 species of Orthoceras, 1 species of Gyroceras, 9 species of Nautilus, 2 species of Sageceras, 2 species of Xenodiscus, 2 species of Arcestes, and 1 species of Cyclolobus. The ammonoids of the Guadalupian are almost entirely different from those of the Salt Range fauna, having, in fact, not one genus in common. The nautiloids form a less satisfactory medium of comparison. In the Salt Range the order was more highly differentiated and many of the species more robust. Foordoceras shumardianum probably belongs to the same group as the two Indian species, Nautilus wynnei and N. transitorius. The other Salt Range groups appear not to be represented here. The Gyroceras is non-Guadalupian, as are the two species of annulated Orthoceras. The two smooth species are more like that from the Delaware Mountain formation.

In his first paper on the Carboniferous of Chitichun Diener cites only Popanoceras trimurti, which is of course non-Guadalupian. In his second paper on this fauna he records Nautilus hunicus, Xenaspis carbonaria, and Cyclolobus walkeri. No appreciable relationship with the Guadalupian is indicated by these forms.

In his second paper dealing with the Spiti fauna Diener cites from the upper division Xenaspis cf. carbonaria, Cyclolobus cf. oldhami, Cyclolobus insignis, C. kraffti, C. haydeni, Orthoceras sp., and Nautilus sp. The only point of contact between the Cephalopoda of this fauna and those of the Guadalupe Mountains is in the Orthoceras, for the species of Nautilus probably belong to different groups.

The only cephalopod which Diener found in his fauna from Kumaon and Gurhwal is Orthoceras sp. It is of the same general type as Orthoceras guadalupense.

A number of cephalopods are known from the Permian Productus shales of Byans. Diener mentions Hyattoceras nov. sp. ex aff. H. cummingsi, Adrianites sp. ind., Gastrioceras sp. ind. ex aff. G. marianum, Brancoceras? sp. ind., Nomismoceras smithi, Pericyclus sp. ind., and Lilinthicoceras sp. ind. This list of forms is generically far different from the Guadalupian. The species of Hyattoceras (which may possibly be congeneric with Waagenoceras cummingsi) and Gastrioceras are not related specifically to the Guadalupian species of Waagenoceras and Gastrioceras.

On the whole only a remote relationship appears to exist between the Guadalupian Cephalopoda and those of the Salt Range and Himalaya. The Guadalupian forms, so far as known, may be somewhat less abundant, varied, and possibly more primitive. It seems probable, however, that further collecting would modify some of these conclusions and perhaps all of them. Both faunas contain this group in less abundance and variety than some which enter into these comparisons.

The only cephalopods cited by Romanowsky from Turkestan are Nautilus dunganensis and Goniatites crenistria. Neither species appears to have any related Guadalupian form.

The Lo Ping fauna contains, according to Kayser, only four species of Nautilus and three species of Orthoceras. The absence of ammonoids is a noteworthy circumstance. One of the Nautili is possibly a Bellerophon (Warthia), and the others are not closely related to the Guadalupian species of Foordoceras. Of the Orthocerata two species belong to the annulated type and are, so far as known, non-Guadalupian. The other is possibly a Dentalium, and at all events its relation to the Guadalupian species of Orthoceras can not be made out.

Loczy found few cephalopods and no ammonoids among the Chinese faunas which he studied. From Kantschoufu he records Cyrtoceras and Orthoceras sp. indet., ?Nautilus (Discites) sp. indet., ?Nautilus kayseri, and Nautilus (Temnocheilus) waageni. These forms appear not to be related to the Guadalupian Ammonoidea and this is the only Carboniferous fauna in which Loczy found any cephalopods at all.

Roemer's paper on the Carboniferous fauna from the west coast of Sumatra cites the following: Nautilus tuberosus, Nautilus sp., Orthoceras undatum, and Goniatites listeri. None of these appears to be related to the Guadalupian Cephalopoda. In writing about this fauna in 1901 Fliegel cites these forms as Orthoceras orientalis, Temnocheilus hayi, Pleuronautilus sumatrensis, and Pleuronautilus loczyi.

Beyrich cites no Cephalopoda, but Rothpletz describes from Timor and Rotti Orthoceras sp., Nautilus sp., Arcestes megaphyllus, Arcestes tridens, and Arcestes persulcatus. They seem to be unrelated to the Guadalupian representatives of this class.

The Cephalopoda of the "Permo-Carboniferous" of Queensland and New Guinea as described by Etheridge are rather few in number and are referred to Nautilus (2 species), Orthoceras (several species), Gyroceras (1 species), and Goniatites (4 species). Only one of the species of Nautilus is figured. As its sutures are unknown and as its sculpture and configuration are so much more like the ammonoids than the nautiloids, it would with greater probability have been placed with the latter group. It resembles several Guadalupian ammonoid species, but as its sutures, and therefore its generic position, are unknown, further comparison need not be made. Only two of the five or six species of Orthoceras are figured. One belongs to an entirely different group from the Guadalupian form, but the other is of the same general type, though much larger. The form described as Gyroceras dubium n. sp. resembles some of the Guadalupian ammonoids, but like the Nautilus its suture is unknown and its generic position problematical. Among the Goniatites recognized by Etheridge is G. micromphalus, originally described by Morris as a Bellerophon. Apparently no specimen thus far found shows any traces of septa, but De Koninck referred it to Goniatites, because he was unable to discover traces of a slit band, a feature usually determinable on most Bellerophons, even when preserved as molds. In the Salt Range of India, however, Waagen obtained a type of Bellerophon in which that structure is missing (Warthia). It is probable, therefore, that Morris's species must be returned to the Bellerophontidæ, and it may even prove to be a representative of the genus Warthia. In general appearance this form, which was obtained from the Bowen River coal field, is suggestive more of Warthia americana than of any other Guadalupian type. The remaining species of Goniatites are imperfectly known. Their suture lines have not been determined and their generic position is consequently uncertain. No effective comparisons can therefore be made with the Guadalupian ammonoids, and I see no relationship between them, the Australian forms apparently representing older, or at all events more primitive, types, so far as can be determined.

In his monograph on the Carboniferous faunas of New South Wales, De Koninck recognizes only two species of Goniatites, both from the "Permo-Carboniferous" division. G. micromphalus, as suggested above, is probably a Bellerophon, to which genus it was originally referred. The same may in fact be true of the second species, for its suture is not known, nor in fact is it certain that it was divided by partitions. Orthoceras is represented by O. striatum, a species perhaps of the same general character as O. guadalupense.

Trautschold identifies only a few cephalopods in the Russian Moskovian, referring them to Nautilus tuberculatus, N. clitellarius, N. subsulcatus, N. eccentricus, N. oxystomus, Orthoceras ovale, and O. polyphemus. None of these is related to the Guadalupian species except Orthoceras polyphemus.

The only records of the occurrence of this group in the Gschelian stage have been in lists, where I have seen recorded three or four species of Orthoceras and three or four species of Nautilus, together with the ammonoid genera Agathoceras and Pronorites. The ammonoids appear to be much less well developed than those of the Guadalupian, but further comment than this would not be justified.

In considering the cephalopods of the Artinsk one recurs at once to Karpinsky's monograph on "Die Ammoneen der Artinskstufe." By title this work of course excludes the Nautiloidea. It treats of 3 species of Pronorites, 3 species of Parapronorites, 4 species of Medlicottia, 2 species of Propinacoceras, 6 species of Gastrioceras, 1 species of Glyphioceras, 1 species of Paralegoceras, 3 species of Agathoceras, 13 species of Popanoceras, 2 species of Thalassoceras, and 1 species of Paraceltites. This list indicates a facies considerably different from the Guadalupian, the only genera in common being Agathoceras, Paraceltites, and Gastrioceras. Agathoceras texanum is closely related to A. uralicum, but the Guadalupian species of Gastrioceras belong to a different group from those treated by Karpinsky. The most abundantly represented of the Russian genera (Popanoceras) does not occur among the known Guadalupian cephalopods, and there seems to be slender relationship between the two faunas in this respect.

Stuckenberg, besides listing several species of Gastrioceras, Pronorites, Popanoceras, and Medlicottia from the Artinsk and the associated Kungurstufe, cites also Nautilus and Orthoceras. These last when figured do not appear to be closely allied to the Guadalupian Orthoceras and Nautilus.

Krotow's account of the fauna of the Artinsk sandstone notes 4 species of Orthoceras, 1 species of Cyrtoceras, 3 species of Nautilus, 11 species of Goniatites, 3 species of Waagenia, and 3 species of Medlicottia. Of the two figured species of Orthoceras one resembles O. guadalupense and one does not. The species of Cyrtoceras is not figured, but presumably is non-Guadalupian, as is the only illustrated species of Nautilus. Krotow uses Gastrioceras, Glyphioceras, Popanoceras, and Pronorites as subgenera of Goniatites. Gastrioceras jossæ appears to be more or less closely related to the Guadalupian species of Gastrioceras, but otherwise the Guadalupian ammonoids and those recorded by Krotow from the Artinsk are different.

The cephalopods of the Russian Permian seem practically confined to the Nautiloidea. Tschernyschew cites from the Government of Kostroma Nautilus freieslebeni and N. cornutus. The former, which alone is figured, appears to be unlike the Guadalupian Foordoceras. N. cornutus is the only cephalopod cited from the Permian by Golowkinsky, and is also not closely allied to the Guadalupian Nautiloids. Netschajew records the same species, together with unidentified and unfigured ones.

In addition to the works above discussed, which deal with the Russian cephalopods, it remains to speak of a few others. Marie Tzwetaev, in 1888, described the cephalopods of the upper portion of the Carboniferous limestone of central Russia, recognizing 1 species of Gastrioceras, 16 species of Nautilus, and 4 species of Orthoceras. The single Gastrioceras does not belong to the same group as the Guadalupian species. The only Nautilus which can be compared with the Guadalupian Foordoceras is N. tschernyschewi, and many of the others are widely different. Of the Orthocerata none is really close to Orthoceras guadalupense, the nearest being probably O. laterals.

Jakowlew also described some Russian Cephalopoda, namely, 2 species of Metacoceras, 3 species of Temnocheilus, 1 species of Pteronautilus, 1 species of Asymptoceras, 1 species of Cœlonautilus, 1 species of Discites, and 1 species of Orthoceras. Metacoceras variabile and M. trigonotuberculatum are not unlike the Guadalupian forms which I have referred to Foordoceras. The remainder of the Nautili, together with the single species of Orthoceras, are not related to the Guadalupian representatives of these groups.

Lastly, De Verneuil, recording no cephalopods from the Permian, describes as from the Carboniferous 2 species of Orthoceras, 4 species of Nautilus, and 10 species of Goniatites. Both the Orthoceratites are of the same general type as O. guadalupense, but none of the Nautili is closely related to the Guadalupian Foordoceras. Goniatites jossæ and to a less degree G. marianum are somewhat closely related to the two Guadalupian species of Gastrioceras, but the other Goniatites have no corresponding forms.

In conclusion, the Cephalopoda do not indicate a close relationship between the Guadalupian fauna and that of any horizon of the Russian section. Because no ammonoids are known from the Russian Permian, the relationship, such as is manifested at all, is rather with the Artinskian stage.

This group appears well represented in the fauna from Djoulfa, in Armenia, described by Abich. This author cites Goniatites striatus, Ceratites djoulfensis, C. intermedius, C. tropitus, C. trochoides, C. pessoides, Nautilus eccentricus, N. propinquus, N. parallelus, N. convergens, N. concavus, N. dolerus, N. dorso-armatus, N. pichleri, N. tubercularis, N. dorsoplicatus, N. armeniacus, Orthoceras annulatum, O. cribrosum, O. transversum, O. bicinctum, O. margaritatum, and O. turitellum. The form identified as Goniatites striatus does not seem to be closely allied to the Guadalupian species of Gastrioceras, while the five species of Ceratites are widely different from anything in that fauna. Among the numerous species which Abich places under Nautilus the only ones which are comparable to the Guadalupian Foordoceras are Nautilus tubercularis and to a less degree N. pichleri. Some of the other species are widely different. Nearly all of the six Armenian varieties of Orthoceras belong to the annulated type, which is unknown as yet in the Guadalupian.

When Arthaber discussed the Djoulfa fauna, a few years ago, he made a number of changes in the generic appellations, but added relatively few new species to those described by Abich, although combining some of them. Thus, instead of Nautilus alone, he gives us Nautilus, Pleuronautilus, and Cœlonautilus, while among the ammonoids we have Gastrioceras, Hungarites, and Otoceras. In its ammonoids the Armenian fauna is widely different from the Guadalupian, for the species of Gastrioceras in each are not closely related. The Orthocerata and the nautiloids are more varied and in the main considerably different.

The Fusulina limestone of Palermo has furnished a much more extensive cephalopod fauna than the Guadalupian is known to contain. Gemmellaro has distinguished among the nautiloids no less than 18 species, representing the genera Trematodiscus (1 species), Pleuronautilus (1 species), Endolobus (1 species), Gyroceras (1 species), and Orthoceras (14 species). The nautiloids are but distantly related to those of the Guadalupian fauna. Gemmellaro's species of Orthoceras for the most part resemble O. guadalupense in being small, gradually enlarging, without constrictions, and with a centrally situated siphuncle. They show more or less extensive differences in the height of the chambers and in the sculpture, a character which I have been unable to observe, my specimens occurring as molds. Some of Gemmellaro's species, such as O. adrianense, O. paternoi, and O. subtriangulare, are non-Guadalupian, so far as known. Two species (O. obliquesulcatum and O. œhlerti) are not figured in my copy of Gemmellaro's report, but the latter is also non-Guadalupian. Though some of the Sicilian Orthocerata doubtless resemble the Guadalupian species rather closely, they are in strong contrast with the latter, by reason of their much greater abundance and differentiation. The nautiloids, on the other hand, while possibly no more abundant, are more varied and different.

In his first paper on the Sicilian ammonoids Gemmellaro discriminated in all 54 species, belonging to the following genera:

In an appendix published subsequently he discusses or describes the following:

The two Guadalupian species of Gastrioceras belong to the same group as the Sicilian forms G. zitteli and G. roemeri. G. sosiense and G. waageni have as yet no cognate Guadalupian species. Paraceltites elegans is closely allied to several Sicilian species of Paraceltites. Agathoceras texanum, however, presents several points of difference from the Sicilian forms, so as to raise some doubt whether they do not at least belong to another section of the genus. The single Guadalupian species of Waagenoceras is related to the Sicilian representatives of the genus. Although, so far as known, much less varied, the Guadalupian Ammonoidea appear to be closely related to those from Palermo, more closely than to any fauna yet brought to light. With the exception of Peritrochia all the Guadalupian genera occur in Sicily.

The cephalopods of the Trogkofelschichten have not yet, so far as I have discovered, been described, and the only record from that section which I have come upon was made by Gortani, who cites from the Carnic Alps only Orthoceras cf. calamus De Kon.

In the Dyas, as in the Russian Permian, the cephalopods are represented only by the Nautiloidea. Geinitz cites two species of Nautilus and one of Orthoceras. The two nautiloids are quite unlike those of the Guadalupian fauna, but the Orthoceras is of the same general type. Similarly, in the English Permian King records only two species of Nautilus, and both belong to different groups from the Guadalupian Foordoceras.

The only Arctic cephalopod which I have seen mentioned is Orthoceras sp. cited by Toula from Nova Zembla. It resembles O. guadalupense.

From Igidi, in the West Sahara, Stache cites an undetermined Orthoceras of a different type from O. guadalupense.

No records of this group having been found from South or Central America from horizons which concern the present investigation, it remains only to speak of the cephalopods of the Pennsylvanian and Permian of North America. Weller lists the Pennsylvanian Ammonoidea under the following genera:

To offset these, the Guadalupian fauna, so far as known, presents but two species of Foordoceras and one species of Orthoceras. Orthoceras guadalupense belongs to a group which is found the world over, at various horizons. O. rushense may be mentioned as a related Pennsylvanian species, and there are others. The genus Foordoceras, to which the Guadalupian species have been referred, is chiefly Indian in its distribution and has not been recognized in the Pennsylvanian. It may prove, however, that Foordoceras shumardianum has cognate species in the Pennsylvanian, especially among the unfigured types of Nautilus.

The ammonoids of the Pennsylvanian include the following genera, according to the recently published monograph of J. P. Smith:

There are in addition three species whose generic position could not be determined. From this list it would appear that the ammonoids of the Guadalupian fauna are much less differentiated than those of the Pennsylvanian and not very different generically, three out of the five Guadalupian genera occurring in the Pennsylvanian also. As regards the former point, except possibly for the higher beds of the Carboniferous in Texas, my experience would show that ammonoids are much more abundant and varied in the Guadalupian than in a corresponding amount of material from the Pennsylvanian. Regarding the other particular, the generic comparison is perhaps a little misleading, for while the Guadalupian species of Waagenoceras is closely related to W. cumminsi, the Guadalupian Gastrioceras and Agathoceras probably belong to different specific groups from the Pennsylvanian congeners.

On the whole, the Cephalopoda of the Guadalupian do not seem to indicate a close relationship with the Pennsylvanian. Such as is suggested lies distinctly between the Guadalupian and the younger beds of the Carboniferous as developed in the Texas region.

Family ORTHOCERATIDÆ Broderip.

Genus ORTHOCERAS Breynius.

ORTHOCERAS GUADALUPENSE n. sp.

Pl. XXIII, figs. 10 to 10b.

Shell circular in cross section, small, slender, gradually tapering. Siphuncle rather large, central. Septa moderately concave, about 2 mm. apart.

The single fragmentary specimen obtained has a length of 11 mm., with a diameter of about 5.5 mm. above and 4.75 mm. at the lower end. Five chambers are included within this measurement of 11 mm., together with the convexity of one chamber. The surface was possibly marked by faint concentric striæ, but appears on casts of the exterior to be smooth.

Horizon and locality.—Delaware Mountain formation. Guadalupe Point, Guadalupe Mountains, Texas (station 2931).

Family TAINOCERATIDÆ Hyatt.

Genus FOORDOCERAS Hyati.

FOORDOCERAS SHUMARDIANUM n. sp.

Pl. IX, figs. 26 to 27a.

Shell rather small, somewhat rapidly enlarging. The transverse section is more or less that of a rectangle, with the width slightly greater than the height. The sides are flattened and nearly parallel. They are marked by well-defined pilæ, which appear to be slightly curved, with the concave side directed toward the aperture. The pilæ terminate above in nodes and the distance between them is about the same as their own length. The ventral arch is broad, the chief curvature occurring at the abdominal angle. There is also a distinct umbilical shoulder which, where the shell is not exfoliated, is marked by an abrupt change in direction. The angle thus produced is emphasized by slight depressions above and below. The depressed zone is narrow, not so broad as either the umbilical or lateral zones, which are about equal in width.

The venter is marked by fine but distinct transverse lines, the direction of which indicates the presence of a rather deep, broad hyponomic sinus. On the lateral and umbilical zones these appear to become slightly stronger, more regularly arranged and sublamellose. On these areas also they are crossed by revolving lines, which are both fainter and finer than the transverse ones.

The flexures of the sutures are all gentle. The entire ventral area is occupied by a broad, shallow lobe; a low saddle falls upon the abdominal shoulder; a second shallow lobe occurs on the lateral zone, while from the umbilical shoulder to the edge of the depressed zone the suture is practically straight.

The siphuncle is nearly central in the mature portion of the shell, but becomes more ventral in the earlier stages.

This species seems to belong to the group for which Hyatt proposed the term Foordoceras, and which is found chiefly in the Salt Range of India. It probably is a member of the Goliathus section, as recognized by Hyatt, but differs in having a proportionately narrower venter and a more distinct umbilical shoulder. The shape is in fact more like the transitorius section, but it does not have the depressed median belt along the venter which characterizes that division. The Indian shells are not described as having the surface ornamentation possessed by the present species, but the revolving lines which are its most peculiar feature are confined to the sides, where they might easily be concealed.

Horizon and locality.—Middle of Capitan formation, Capitan Peak, Guadalupe Mountains, Texas (station 2926).

FOORDOCERAS SHUMARDIANUM var. PRÆCURSOR n. var.

Pl. XXV, figs. 15 to 15b.

This species is related to the preceding and has, in fact, about the same general aspect. A careful inspection, however, reveals differences which render it impossible to consider them the same. The septa are somewhat more closely arranged. There is no sharply defined umbilical shoulder, and the growth lines, which are clear and very elegant over the small area of surface preserved in my specimen, show a considerably deeper hyponomic sinus. Like the foregoing, this species is marked on the umbilical and lateral zones with transverse and revolving lines, which produce a reticulated surface ornamentation.

Horizon and locality.—Basal black limestone, Guadalupe Point, Guadalupe Mountains, Texas (stations 2920 and 2967).

Family PRONORITIDÆ Smith.

Genus PERITROCHIA n. gen.

This term is proposed for a shell from the black limestone, whose generic characters appear to be the following: Shell subglobose. Whorls deeply embracing, so that the umbilicus is nearly or quite closed. Aperture indented to nearly half its height by the preceding volution, and strongly lunate. Of the suture, the ventral lobe is bifid, possibly trifid. The lateral lobes are numerous, at least four on each side. The first lateral lobe is bidentate; the other lobes and saddles are simple, with rounded ends. The surface is without nodes or keels and apparently with only obscure growth lines.

It is with much hesitation that I have introduced a new generic name for this Guadalupian type and only after many comparisons with known genera. The most closely related genus is Pronorites. The suture of Pronorites is almost exactly that of Peritrochia, save that there is a tendency in the lobes toward a pointed, linguiform shape. The shape of the shell in Pronorites, however, is discoidal and the whorl section elongate and subquadrate, while the shell in Peritrochia is globose and the whorl section transverse and lunate. The umbilicus in one is wide and in the other closed.

PERITROCHIA EREBUS n. sp.

Pl. XXV, figs. 9 to 11.

Shell small, compressed-spherical. Whorls highly arched, deeply embracing. Abdomen somewhat narrowly rounded. Aperture lunate. Umbilicus minute or closed. Surface smooth, apparently without either striæ, nodes, or carinæ. Ventral lobe bifid, possibly trifid. The first lateral lobe is bifid; the remaining lobes and saddles small, rounded, rather deep, with straight sides. There are five lateral saddles on each side, and possibly a sixth small one in the extreme umbilical region. The character of the ventral lobe is not known with certainty.

This species is common in the black limestone, but has not yet been found at any other horizon.

Horizon and locality.—Basal black limestone, Guadalupe Point, Guadalupe Mountains, Texas (station 2920).

Family PROLECANITIDÆ Hyatt.

Genus PARACELTITES Gemmellaro.

PARACELTITES ELEGANS n. sp.

Pl. XXV, figs. 12 to 14.

The general shape of this species is discoidal, much compressed. The growth is extremely evolute, each whorl embracing the preceding one to the extent of only about one-sixth. The general shape of a section across one of the volutions is elliptical, with the length about twice the breadth. The outer end is, however, slightly narrower than the inner, which, in addition to being expanded, is indented below by contact with the preceding whorl. The largest specimen noted is 25 mm. in diameter.

The sutures are rather simple. There is a siphonal lobe whose character has not been completely determined. In some specimens it appears to be merely flattened, in others to be slightly elevated at its base and indented so as to form two denticles. Again, it sometimes appears to have three denticles. Probably there are two denticles, for the best preserved and clearest specimens seem to have this structure, the other appearances being due to preservation. There are two lateral saddles and two lateral lobes, both lobes and saddles being simple and rounded. The saddles are a little broader than the lobes, and all decrease in strength laterally. Owing to the small area of contact between the volutions, the internal sutures are simple. There is a lateral saddle, half of which is external and half internal, and an antisiphonal lobe, which is narrower than the siphonal one and possibly not denticulate.

The surface is entirely devoid of revolving lines and is probably smooth except for rather regularly arranged transverse plications, which begin at the umbilicus and extend nearly to the ventral surface. Sometimes they have a slightly sigmoid curvature. The plications vary somewhat in closeness of arrangement in different specimens and on the mature or senile portions appear to become at the same time finer, more closely arranged, and less strongly marked.

There can be no doubt that the present form belongs to the genus Paraceltites, and it is even closely related to Gemmellaro's species. The resemblance is strongest with P. hoeferi and P. halli, but P. elegans can hardly, I believe, be regarded as identical with either of them. One difference which can be named is the more nearly transverse direction of the plications in P. elegans, while in the Sicilian species they slope forward.

Horizon and locality.—Basal black limestone, Guadalupe Point, Guadalupe Mountains, Texas (station 2967). Middle of Delaware Mountain formation, Delaware Mountains, Texas (station 2968).

Family GLYPHIOCERATIDÆ Hyatt.

Genus GASTRIOCERAS Hyatt.

GASTRIOCERAS ? SERRATUM n. sp.

Pl. XXIII, figs. 9 to 9d.

Shell small, discoidal. Umbilicus wide, open. Ventral surface broad and flattened, aperture subelliptical, gently concave below, slightly embracing the preceding whorls at the sides.

Surface marked laterally by very prominent, oblique, somewhat curved angular ridges. The main portion of the ventral surface is free from these projections, but is crossed by a number of fine revolving striæ, which extend onto the lateral ridges. There are also annular constrictions, about three in a volution, which are not straightly transverse, but are gently concave across the venter, then bent sharply backward at the sides, following the oblique direction of the lateral ridges.

The suture has been made out with some precision, but yet is not known in every detail. The siphonal saddle is small and presumably bidentate. There are two lobes and two saddles on each side, both lobes and saddles being rounded and rather weak. The second lateral lobe occurs at the margin of the ventral surface, the rather narrow side of the whorl being occupied by a lateral saddle. The lobes are conspicuously narrower than the saddles. The sutures appear to be independent of the lateral ridges, the second lateral saddle occurring just in front of or just behind a ridge indifferently.

In its specific relations this form is clearly distinct from any American species as yet described, and is more closely allied to types which occur in the late Carboniferous or Permian of Europe.

Horizon and locality.—Delaware Mountain formation, Guadalupe Point, Guadalupe Mountains, Texas (station 2931). Delaware Mountain formation, southern Delaware Mountains, Texas (station 3500?).

GASTRIOCERAS sp.

Pl. XXIX, figs. 22 and 22a.

The adult form is discoidal, the whorls probably moderately evolute and crescentic in cross section. The umbilicus is large and open. The sutures are unknown.

The sculpture consists of strong, transverse plications which extend a short distance up from the umbilicus, and strong, coarse, revolving liræ which are chiefly developed over the ventral surface. In the specimen figured, which has a diameter of 35 mm., there are three plications in 5 mm. and about five revolving liræ in the same distance. The liræ are strong and abruptly elevated. Constrictions appear to be wanting.

As the suture is not known, there is still some doubt as to the generic position of this form, though with great probability it can be assigned to Gastrioceras. It resembles several Pennsylvanian forms, especially G. branneri, but differs from any of them in having the strong revolving liræ. In this respect it resembles some of the forms described by Gemmellaro from the Sicilian Permian. Although probably a new species, I feel that it will be unwise to designate it by a new name without better material and more complete data.

Horizon and locality.—Delaware Mountain formation, southern Delaware Mountains, Texas (station 2968).

Family POPANOCERATIDÆ Hyatt.

Genus AGATHOCERAS Gemmellaro.

In this generic group but one species is included, the relations lying more with Agathoceras than with any genus with which I have made comparisons. There are several important differences, however, between the present form and typical Agathoceras. One of these resides in the sculpture, in which respect the Guadalupian species, while possessing a certain sort of revolving liration, has nothing of this nature to compare with the strong revolving liræ of the Sicilian species. Again, as to the sutures, while the lobes and saddles are about the same in number in both types, and simple, both the flexures are rounded in A. texanum, whereas in typical Agathoceras the lobes are linguiform and pointed, only the saddles being rounded.

Forms more like the present have been figured by Karpinsky from the Russian Artinsk. Several of his species are represented with the lobes as well as the saddles rounded, and A. krotowi is figured with one less saddle than typical Agathoceras, a condition which appears to exist in the present species. Finally, the sculpture in A. stuckenbergi seems to be more like the Guadalupian A. texanum than that of the Sicilian forms.

AGATHOCERAS TEXANUM n. sp.

Pl. XXV, figs. 8 and 8a.

The shell in this species is rather thick, discoidal, strongly involute, with a small umbilicus. The whorls are broadly crescentic in cross section and deeply embracing. Constrictions are apparently absent. There is a rather high, narrow, siphonal saddle, followed by three lateral saddles and three lateral lobes, a fourth lateral lobe lying just on the umbilical shoulder. The internal sutures are unknown. The lobes and saddles are all simple and all rounded, though perhaps not quite symmetrically so. The siphonal saddle is lower and narrower than the other saddles, and the adjacent lobes are narrower than the other lobes, but otherwise the lobes and saddles are approximately equal, gradually losing in height and becoming relatively broader toward the umbilicus.

The surface is without transverse plications or strong revolving lines. It has, however, a delicate sculpture, different from that of typical Sicilian Agathoceras, but somewhat resembling that of a species from the Artinsk. It is crossed transversely by delicate, very finely zigzag lines, from which discontinuous liræ extend alternately forward and back, uniting corresponding points in the adjacent transverse lamellæ. There results a surface somewhat suggesting that of a tile roof.

Horizon and locality.—Basal black limestone, Guadalupe Point, Guadalupe Mountains, Texas (station 2967).

Family CYCLOLOBIDÆ Zittel.

Genus WAAGENOCERAS Gemmellaro.

WAAGENOCERAS CUMMINGSI var. GUADALUPENSE n. var.

Pl. XXIX, figs. 23 to 26.

This species appears to be abundant at station 2965, in the Delaware Mountains, but unfortunately our material is in such a condition that to study it satisfactorily is not possible. Although preserved in limestone, the original shell substance appears to have been macerated in a way which is frequently observed in a shaly matrix, with the result that the sutures are not as a rule preserved, and not only is this true of the outside of specimens which have weathered out from the rock, but even when these are broken open nothing is seen. One or two specimens in which the sutures are preserved are either worn, crushed, or immature.

The general shape appears to be that of the genus Waagenoceras, specimens having a flattened, subglobose shape, with crescentic whorl section. The whorls are strongly embracing, leaving but a narrow umbilicus. Evidently the suture was strongly complicated, but in the best specimens it is difficult to follow the individual sutures consecutively. There appear to have been six saddles and seven lobes, or possibly more, on the external portion of mature shells. All the lobes and saddles appear to be strongly digitate.

The shell having in every instance been removed the character of the surface can not be determined. No evidence of sculpture of any description remains, not even of constrictions, a fact which is somewhat against the identification as Waagenoceras, and it is doubtful if this feature could have been lost in all instances through erosion.

The Guadalupian form appears to be rather closely related to Waagenoceras cummingsi White. It is a smaller form, with narrower umbilicus and certain appreciable differences in the suture. The sutures are more closely arranged, the lobes and saddles probably more numerous, the lobes less deeply digitate, and the saddles more symmetrically rounded.

Horizon and locality.—Delaware Mountain formation, southern Delaware Mountains, Texas (station 2965).