Geological Survey Professional Paper 58 The Guadalupian Fauna

ARTHROPODA.

CRUSTACEA.

Crustacea are poorly represented in the Guadalupian, a condition which is apt to prevail in the higher faunas of the Carboniferous. I have found only one species of Bairdia, one of the Argillœcia, and one of Cythere(?) among the ostracods, and two species of trilobites (Anisopyge perannulata and A. antiqua). The latter representatives of a primitive group are in general of more than usual interest, and these Guadalupian forms particularly so, since they appear to constitute a hitherto unrecorded modification of the type. They are, furthermore, rather abundant at the horizon which they especially characterize.

It is a matter of some interest that this group is very rare in the fauna of the Salt Range in India. Thus far no trilobites are known from that region, and only one specimen representing the ostracods, referred to the genus Cythere, has been obtained.

Trilobites are known in the Himalayan region, however, as Diener cites a species of Phillipsia in his paper on the fauna of Kashmir and Spiti. It is very different from the Guadalupian trilobites. Again, from the Chitichun fauna No. 1 a new species of Phillipsia and a new genus and species, Cheiropyge himalayensis, were described by the same author. Neither form is related to the trilobites of the Guadalupian.

In the Lo Ping fauna Kayser described Phillipsia obtusicauda, a singular type, very different from the Guadalupian trilobites. In the fauna from Kantschoufu Loczy found Phillipsia kansuensis, and in that from Tschungtjen, province of Yunnan, Phillipsia sp. indet. Neither of these forms, so far as can be told, shows any significant relationship with the two Guadalupian species of Anisopyge.

Beyrich found a small trilobite amongst his fossils from Timor and Rotti, which he described as Phillipsia? parvula. Roemer described Phillipsia sumatrensis from Padang, on the west coast of Sumatra. This species belongs to Gemmellaro's recently established genus Pseudophillipsia, and is strongly different from Anisopyge. It was placed by Fliegel in the genus Griffithides, and appears to be rather common. When compared with those of Roemer, Fliegel's figures show some differences in the configuration of the glabella which seem important.

Etheridge cites but a small number of Crustacea from the "Permo-Carboniferous" of Queensland and New Guinea, the list comprising one ostracod (Beyrichia varicosa) and of the trilobites three species of Phillipsia and one of Griffithides. These forms are not related, save in the most general way, to the Guadalupian Crustacea.

The Crustacea of the Carboniferous fauna of New South Wales consist of ostracods and trilobites. The ostracods comprise but two species, referred to the genera Polycope and Entomis, neither of which has been recognized in the Guadalupian. The three species of trilobites came from the lower portion of the Carboniferous series and do not concern this discussion.

Trautschold's monograph on the fauna of the Russian Moskovian contains citation of three species of Phillipsia, related in no instance to the Guadalupian trilobites.

From the Gschelian Phillipsia or Griffithides gruenewaldti is cited by several authors. Stuckenberg records Phillipsia gruenewaldti, Phillipsia cf. roemeri, and Brachymetopus sp.

In the Artinsk Stuckenberg found Phillipsia gruenewaldti, Phillipsia cf. roemeri, and Bairdia curta. The Kungurstufe furnished him only Bairdia sp. Krotow cites from the Artinsk Cythere sp., Estheria subconcentrica, Estheriella trapezoidalis, and E. oblonga. In another paper this author cites Phillipsia gruenewaldti, Cythere curta, and Kirkbya permiana from the Artinsk.

From the Permian of Russia Netschajew records only Ostracoda and Phyllopoda, including 6 species of Bairdia, 6 species of Cythere, and 1 species of Leaia. It would appear, so far as one may judge from these incomplete data, that in the Russian section trilobites of the ordinary Carboniferous type persisted, into the Artinsk and were replaced in the Permian by bivalve Crustacea, which, though of sporadic occurrence at lower horizons, are there much more numerous. Very different are the conditions in the Guadalupian, where the trilobites are fairly common, but are not of the ordinary Carboniferous type, where ostracods are rare and where phyllopod Crustacea, which seem to be abundant in the Russian Permian, are not known at all. This difference, however, may be taken to indicate difference of environment as well as, or instead of, difference of geologic age, for Estheria and Leaia usually occur in impure or brackish-water sediments, a set of conditions which is also strongly implied for the Permian by the abundance of nonmarine pelecypods.

The Guadalupian Crustacea present important differences from those of the fauna which Gemmellaro described from Palermo. The Sicilian Crustacea, in fact, are much more extensively developed and play a much more important part in the fauna than do the Guadalupian forms. Of the trilobites Gemmellaro cites 2 species of Proetus, 4 of Phillipsia, 1 of Griffithides, and 1 of Pseudophillipsia. The macrouran decapods are also represented by the genus Palæopemphix (3 species), and the brachyourans by Paraprosopon (1 species), and Oonocarcinus (3 species). Of the ostracods, Gemmellaro cites Cypridinella (2 species), Cypridellina (1 species), Cypridella (2 species), Cypridina (4 species), Philomedes (1 species), Entomoconchus (1 species), Entomis (2 species), and Beyrichia (1 species). No matter whether we consider the trilobites or the ostracods, they are much less differentiated in the Guadalupian fauna, while the decapods are not known there at all.

I have failed to find any account of the Crustacea of the Carnic Alps, save that given by Gortani, and his fauna is, I believe, older than that of the Trogkofelschichten, which is especially interesting in the present comparisons. Unfortunately the Trogkofel Crustacea have not been described. Gortani cites a species of Phillipsia, one of Griffithides, and one of Brachymetopus. His figures are poor, but the species appear to have no close connection with Anisopyge of the Guadalupian.

In the German Dyas again the Crustacea are an important factor in the fauna. Geinitz cites Hemitrochiscus (1 species) and Prosoponiscus (1 species) among the decapods. Much more abundant are the ostracods, of which 26 species are cited, 25 being referred to Cythere and 1 to Kirkbya.

In the English Permian trilobites have not been found, but ostracods are fairly abundant. King recognizes ten species of Cythere, Bairdia, etc. He also describes two species of phyllocarid Crustacea under the titles Dithyrocaris permiana and D. glypta. The Guadalupian fauna differs from the English Permian in the presence of trilobites, the absence of phyllocarids, and the more rare occurrence of ostracods, although the character of the latter is, so far as it goes, much the same.

From Nova Zembla Toula cites Phillipsia gruenewaldti; that species, however, is but remotely related to the Guadalupian Anisopyges.

Stache found only Cythere sp. in the Carboniferous limestone of the West Sahara (Igidi).

A great variety of Crustacea have been described from the American Pennsylvanian, although they are seldom abundant or varied at any one place. Among the trilobites there have been discriminated 3 species of Griffithides, 5 of Phillipsia, and 1 of Proetus. Apparently these are all generically distinct from the Guadalupian trilobites. The other groups of Crustacea, according to Weller's bibliography, subsequently described forms being neglected, make up a long list, as follows:

This is very different from the Guadalupian fauna, although chiefly in the way of greater differentiation. The phyllocarids, the limuloids, and the decapods, all represented in the Pennsylvanian, are lacking in the Guadalupian, although as they are but rarely encountered in the former their apparent absence in the latter does not carry much weight, at least until the Guadalupian has been far more extensively collected.

Order TRILOBITA.

Family PROETIDÆ Barrande.

Genus ANISOPYGE n. gen.

This seems to be one of the last survivors of the trilobite group, and while it can almost certainly be referred to the Proetidæ, it probably represents a genus distinct from any of those at present recognized as belonging to that family. From among the numerous peculiarities already shown by our imperfect knowledge of this form it is difficult to discriminate precisely the characters of generic importance from those which are specific and individual. Some of the seemingly more important, however, which may be regarded as discriminating it in a generic way, are here set forth. In the cephalon are to be noted the low convexity, the wide border, the glabella much enlarged in front and divided by strong marginal furrows, and the absence of genal angles. These characters appear singly in other genera of the Proetidæ, but not, I believe, in combination. A character which seems to be peculiar to the present form is the limitation of the fixed cheeks to the eye lappets. In the pygidium the folding under of the border, the development of a smooth band along the edges of the axis, the great number of the axial lobes and their independence of the lateral lobes, are the important characters, unknown, so far as I am aware, at least to the degree here present, in others of the Proetidæ. The entire lack of connection between the lateral and axial lobes shown by the large and variable number of the one and the small and constant number of the other, the separation of which by the development of an unsegmented band on the axis must perhaps be regarded as a correlated phenomenon, is an interesting case of specialization in this organ.

Without much doubt Phillipsia is the nearest related of the Proetidæ to the present type, and I am not sure to what degree the latter is entitled to discrimination. In the cephalon the glabella is distinctly more pyriform than in typical Phillipsia or in the majority of species, and the fixed cheeks are more reduced in size, but the lines of the facial suture are essentially the same and also the furrows of the glabella. The failure to extend the genal angles into spines is not unknown in Phillipsia, though most of the species seem to have spines. I do not know to what extent the structure of the eye, which appears to be solid on the exterior side and faceted only on the interior, will afford distinctive characters. It may prove important. Phillipsia has 9 thoracic segments and the present genus, so far as known, but 7, a difference, even if corroborated, of no very great degree. In the pygidium the differences are perhaps as marked as anywhere. The axial and the lateral, segments in Phillipsia are very nearly the same in number, and they are in fair correspondence. It is only toward the tip of the pygidial axis that the segments multiply more rapidly than the lateral ones. Woodward describes the axis of the pygidium of Phillipsia as composed of 12 to 16 segments. The axis of the typical species of Anisopyge contains about 30 segments, and there is a very striking discrepancy between the segments of the axis and those of the pleural regions, a discrepancy emphasized by the presence of an unsegmented band along either side of the axis.

On account of these differences it did not seem desirable to retain under Phillipsia Shumard's Guadalupian fossil described as P. perannulata. Pseudophillipsia, which Gemmellaro described from a fauna in many ways much resembling that of the Guadalupe Mountains, is a still more strongly differentiated genus.

In one respect Anisopyge is very similar to the Himalayan genus Cheiropyge, i. e., in the very unequal segmentation of the axial and lateral portions of the pygidium. The fact that in Anisopyge the pygidium is surrounded by a broad, smooth hand, while in Cheiropyge the lobes are extended so as to give this number a denticulate outline, is an important difference. Comparisons of other portions of the carapace are impossible because only the pygidium of the Himalayan form is known. It is evident, however, that the two types do not represent the same genus.

ANISOPYGE PERANNULATA Shumard.

Pl. XVI, figs. 14 to 19.

1858. Phillipsia perennulata. Shumard, Trans. Acad. Sci. St. Louis, vol. 1, p. 296 (date of volume, 1860).

White [Permian] limestone: Guadalupe Mountains, New Mexico.

1859. Phillipsia perennulata. Shumard, idem, p. 388, pl. 11, fig. 10.

White [Permian] limestone: Guadalupe Mountains, Texas and New Mexico.

1887. Phillipsia perannulata. Vodges, Ann. New York Acad. Sci., vol. 4, p. 84.

Carboniferous: Guadalupe Mountains, New Mexico.

Pygidium deltoid, as wide as long, elevated; border narrow, smooth, inflected behind, outer edge sinuate, inner edge obtusely subangulated, the anterior two-thirds marked with a shallow furrow; posterior extremity narrow, very strongly arched; axial lobe elevated, nearly as wide as one lateral lobe, tapering very gradually from front to posterior extremity, which is bluntly rounded and nearly terminal; axial rings from 28 to 30, rounded, distinct on the dorsum, becoming obsolete on the sides, margins sinuate, surface of each ring studded with a single row of 4 or 5 granules, the granules of 1 ring alternating with those of the adjoining ones, transverse furrows much narrower than the rings and not deeply impressed; lateral lobes arched, somewhat flattened superiorly; segments 8, subangulated, simple, gently arched forward, posterior ones directed obliquely backward, the last one being nearly parallel with the longitudinal axis; transverse furrows deep and rather broad; surface of rings garnished with a row of distinct granules.

Dimensions.—Length and width, 0.74; height, 0.28.

Geologic formation end locality.—White limestone of Guadalupe Mountains, New Mexico. The collection of the expedition contains several examples of the pygidium of this species.

Shumard based this species on the only part known to him, the pygidium, his description of which is quoted above. From more or less perfect material recently collected it is possible to add to his description that of the cephalon and the probable number and character of the thoracic segments.

The general shape of the cephalon is semicircular. The suture is as usual in this family, except as specified below. The glabella is moderately convex and strongly expanded in front, occupying almost the whole cranidium. The border is wide, narrowing at the sides, separated from the glabella by a distinct though not deep furrow, which indents the otherwise even curve made by a longitudinal section through the glabella and border. The neck ring and the posterior portion of the glabella are strongly depressed. The fixed cheeks are limited to the rounded, flaplike projections at the sides of the glabella near its posterior end, which fit into the concave side of the ocular crescent. These flaps are in this species suberect. The glabella bears three, possibly four, marginal furrows, which are slightly curved. Beginning with the posterior one, which is strongly inclined backward, the furrows decrease in length, strength, and obliquity toward the front. The triangular space inclosed between the first lateral furrow and the neck furrow, i. e., the first lobe of the glabella, is elevated centrally into a pointed node or pustule. The second lateral lobe is narrow. It terminates in a second projection, similar to the first, though larger. The third lateral lobe terminates in a third monticule of about the size of the first, but less pointed and less clearly defined. Just in front of the end of the third lateral furrow a fourth small, low elevation is to be seen, with possibly a fourth short indistinct furrow, marginally in front of it. Located centrally in a transverse line with the knobs which terminate the second lateral lobes, another strongly elevated knob occurs. Behind the line thus formed, the glabella is much depressed. The neck ring is broad and is produced laterally into two rather strong, slender, tapering strips. The surface of the border is marked by lines running parallel but not conforming to its margins. The surface of the rest of the cranidium is nearly smooth, being marked by rather indistinct, scattered pustules, which are obvious only on the posterior half, especially on the neck ring.

The free cheeks have a generally triangular shape. They are cut squarely off at the genal angle, not prolonged into spines. The eye is large, reniform, and strongly elevated. Its facets are obscure on the outside but strongly marked on the inside. A broad border surrounds the posterior and lateral side of the free cheek. On the inner side of the lower margin the border becomes gradually narrower, leaving room for the strip which projects from the neck ring. The border is rather strongly convex, as is also the inner portion, the two areas being defined by strongly marked furrows parallel to the margins. In the case of the lower furrow it is parallel to the margin of the cephalon as a whole, the suture, which forms the lower outline of the free cheek, being oblique to it. The inner area defined by the furrows has an approximately triangular shape, its inner angle, however, being strongly truncated by the eye with its surrounding grooves. The lateral border of the free cheek is marked by longitudinal lines, the inner area by a few pustules of rather large size. In one specimen these are restricted to the portion of the area anterior to the eye, in others they are distributed more evenly, though rather sparsely, over the whole.

The pygidium has already been described by Shumard. Some additional facts are furnished by our material. As indicated by his description, the border of the pygidium is somewhat peculiar. Toward the front it is flat and spreading, forming part of the regular transverse expansion. Toward the back its lower border rather suddenly begins to turn inward, so that at the extremity it is doubled under the rest of the shell. In the process about halfway down the side the border often becomes somewhat concave, with a ridge above and one blow. The upper ridge becomes more and more pronounced, as the lower part of the border becomes more and more restricted, until at the posterior extremity it forms the real terminus of the shell. Viewed from above, therefore, the posterior end appears to be without a border, it having been turned under and concealed by the parts lying above. This allows the axis to reach nearly or quite to the posterior outline and gives this end a pinched and pointed appearance. Another feature mentioned by Shumard is that the axial segments did not persist to the primary dorsal furrows, but are regularly limited by a depressed line parallel to these furrows, so that the axis is edged by a rather distinctly defined plain band. There are eight lateral lobes, the number on large and small specimens alike seeming to be constant. The number of axial lobes seems to vary according to size, though this may be only apparent, as in small specimens the terminal ones become so minute and faint that it is impossible to count them with accuracy.

In only one specimen, and that a rather young one, is the number of thoracic segments indicated. In this case the pygidium is preserved with seven of the free segments attached to it, but as the cephalon is missing some of these segments may have been lost with it.

Horizon and locality.—Middle of Capitan formation, Capitan Peak (station 2926); base of Capitan formation, hill southwest of Guadalupe Point (station 2906); "dark limestone," Pine Spring (station 2930); Delaware Mountain formation, Guadalupe Point (station 2931); basal black limestone, Guadalupe Point (station 2967), Guadalupe Mountains, Texas. Delaware Mountain formation, southern Delaware Mountains, Texas (station 2969).

ANISOPYGE? ANTIQUA n. sp.

Pl. XXIV, figs. 23 to 26.

This species, which is discriminated especially for some specimens obtained from the black limestone at the base of the Guadalupian section, is less completely known than A. perannulata. In the present case we have a number of pygidia and an imperfect head shield.

The cephalon is almost too imperfect for detailed description. So far as known it does not differ materially from that of A. perannulata. The glabella appears to be pyriform, and it has three distinct lobes, with possibly a fourth obscure one.

The pygidium is subsemicircular, wider than long, strongly arched. The axis is very strongly elevated, divided into about 16 well-marked segments, each of which is crossed by a row of pustules. The segments lose distinctness along the margins of the axis, where there occurs a moderately well-defined band on which they are rather obscure. The lateral segments are not as strongly marked as those on the axis and appear to number but seven. There is a broad smooth band around the whole pygidium, which narrows and becomes more vertical behind, so that the end of the axis is almost terminal.

This species is readily distinguishable from A. perannulata by the greater width of the pygidium, which has much fewer segments on the axis. The lateral segments also stand more perpendicular, those of A. perannulata, especially the posterior ones, pointing strongly backward.

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

Order OSTRACODA.

Family CYTHERIDÆ Zenker.

Genus CYTHERE Muller.

CYTHERE? sp.

Pl. XVI, figs. 13 and 13a.

Our collections contain only one specimen of this species, and it is somewhat broken. The general shape is oval, a little higher at one end than the other. The lower margin is convex, somewhat more strongly rounded behind. The upper margin is more nearly straight, especially in the middle, more curved at the ends, and slightly converging forward with the base. The convexity is high, being especially inflated just posterior to the middle, behind which it is well rounded, but descends more rapidly to the anterior extremity. The surface appears to be delicately roughened or pitted.

More perfect material representing this species will be necessary before a complete and accurate description can be framed, the foregoing being, however, the best that I could make under the circumstances.

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

Family CYPRIDÆ Zenker.

Genus BAIRDIA McCoy.

BAIRDIA aff. B. PLEBEIA Reuss.

Pl. XXV, figs. 16 and 16a.

This species also is represented in our collections by a single silicified specimen, apparently a right valve. The size is small, about 1-1/3 mm. in width, and the height is less than half that amount. The shape is irregular, pointed at both ends, but more acute and produced behind than before. The upper outline is strongly convex in the middle and slightly concave at both ends. The lower margin is nearly straight in the middle, bending upward at both ends but more at the anterior than at the posterior, and meeting the upper outline more or less abruptly. The convexity is rather strong and inflated toward the middle, with the ends depressed. The surface is apparently smooth.

This species resembles Bairdia plebeia Reuss of the German and English Permian more than any with which I have compared it. It seems to be different, but with only one valve of the Guadalupian shell and no specimen of the European one with which to compare it, I feel unable to arrive at a conclusion on this point.

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

Genus ARGILLŒCIA Sars.

ARGILLŒCIA sp.

Pl. XXVIII, figs. 12 and 12a.

Of this species our collection contains only one valve, which has so symmetrical a shape that I am unable to determine which end is anterior and which posterior, and whether it is a right or a left valve. It so much resembles the English Carboniferous form which Jones and Kirkby described as Argillœcia æqualis a that I have provisionally referred it to the same genus, though it is clearly distinct in its specific relations.

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aAnn. Mag. Nat. Hist., ser. 5, vol. 18, 1886, p. 263, pl. 9, figs. 6a, 6b.

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The shape is regularly elliptical, with broadly and equally rounded ends. The width, which is almost exactly 2 mm., is about twice the height. What must be regarded as the lower margin is nearly straight, while the upper is gently convex. The two margins diverge very slightly toward one end. The convexity is moderate, rather flattened over the mesial portion, and strongest about the margin. The shell is flexed somewhat more abruptly along the lower than the upper border, which occasions the straight outline in the one and the curved outline in the other. Transversely, however, the convexity appears to be symmetrical, without one end higher than the other. The surface is smooth.

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