MOUNTAIN LIZARD. Scelaporus graciosus graciosus Baird and Girard

Field characters.—Size small, total length 5 inches or less; scales everywhere very small, less than 1/16 inch across; those of back, sides and tail ridged or 'keeled'; 42 or more scales in lengthwise row between back of head and line across back of thighs. (See pl. 57a.) General coloration of body above greenish or brownish gray, with 6 lengthwise rows of irregular dark blotches along back and sides; middle of under surface of body and whole under side of tail pale yellow; chin region and sides of belly deep blue in males, light bluish in females, but never with two separate blue patches on throat.

Occurrence.—Common resident in Canadian Zone on west side of Sierra Nevada. Recorded from Pilot Peak ridge and from Chinquapin eastward to Porcupine Flat and to Merced Lake. Also present east of mountains in Canadian and Transition from Walker Lake to Mono Craters. Lives chiefly on ground beneath brush plants, but to some extent around logs and rocks. Active in the warmer parts of summer days.

The Mountain Lizard is common in and about the thickets of snowbush, chinquapin, huckleberry oak, and other brush plants in the Canadian Zone, hence, chiefly above the level of Yosemite Valley. It stays mostly about and beneath the cover of this high mountain chaparral, though it is sometimes to be seen on rocks and on logs. Its habitat is thus rather different from that of the Tenaya Lizard; the latter is more of a climber, to be found on large granite boulders out in the open.

Although we did not find them on the floor of Yosemite Valley, some Mountain Lizards did come to our notice (June 8, 1915) on the uppermost parts of the steep taluses on the north side of the Valley beneath Eagle Peak. The altitude here is about 5000 feet, the lowermost station of ascertained occurrence for the species anywhere in the whole region. In our several trips up the Yosemite Falls Trail the first individuals were met with at the 5750-foot contour. The highest station of occurrence in the region was the summit of Ostrander Rocks, east of Glacier Point, at 8250 feet.

These lizards, like all the other high mountain reptiles, must spend fully half the year in dormancy, hidden away in crevices deep down among rocks or in spaces among the stems of bushes or at the bases of stumps. An early date, seasonally, for noting them is May 27 (1911), when several were seen at noon and shortly after on the bare sunlit surfaces of the rocks at the very summit of Eagle Peak (7700 feet); at that time there was deep snow all about. Our earliest date, at a lower altitude, 6700 feet, near the brink of Nevada Falls, is for May 18 (1919). Our latest record is for October 11 (1914) near Yosemite Point.

The Mountain Lizard is, when fully adult, only about 5 inches in length. The head and body is about 2-1/2 inches long. It is decidedly smaller than any of the other local species, though it might be confused with young of the Fence Lizard. The body of the present species is covered, on the back and sides, with keeled or ridged scales which are of small size. Between the last of the large plates of the head and a line drawn across the back of the thighs there are usually 45 or more scales in a lengthwise row, whereas in the other 'swifts' (races of Sceloporus occidentalis) the scales usually number less than 45 (except in S. o. taylori). (See pl. 57a, b.) An additional character for distinguishing the two is found in the condition of the scales on the back of the thigh; in the present species these are smooth, whereas in the other local Scelopori they are keeled.

An individual of this swift comes to attention usually by reason of the rustling noises it makes as it scurries about in the dry leafy débris beneath the brush plants. Most of its time is spent within this type of surroundings, and it is often difficult to discover or to capture when it takes to the shelter immediately afforded. The food of the species seems to be gathered on the ground; sometimes one of the lizards may be seen running about on the surface of a fallen tree trunk in search of flies and other insects which may be sunning themselves on the rough bark.