APPENDIX C. — REPTILES. 34T 



sented in a state of too great expansion. The head is ovoidal, de- 

 pressed, subconcave above. The occipital plate is heptagonal, 

 broad, and linear posteriorly, pointed and very acute anteriorly. 

 It is surrounded by twelve smaller plates, six of which, very small, 

 line the posterior edge, while the dlher six are distributed on the 

 remaining circumference, three to the right and three to the left. 

 There are two vertical plates, the anterior one the largest and pen- 

 tagonal. In advance of the latter, seven or eight polygonal frontal 

 plates form a conspicuous group, while near the extremity of the 

 snout the plates are as minute as the scales on the neck. The 

 plates which line the margin of the jaws are small, narrow, elon- 

 gated, and inconspicuous. On the chin there are three pairs compa- 

 ratively larger and conspicuous. The scales on the back are spade- 

 shaped and strongly carinated from the neck to the tip of the tail. 

 On the latter region they are a little more acute posteriorly and 

 verticillated. On the sides of the abdomen they are smaller, and 

 their outline less regular. The abdominal scales are smooth, 

 irregularly lozenge-shaped, bidentated posteriorly as in S. scalaris. 

 The opening of the ear is subtriangular, protected by several pro- 

 jecting scales arising from its anterior edge. The toes and nails 

 are very slender ; the latter are proportionally long and slightly 

 curved. When the fore legs are stretched backward, the tip of 

 their toes will reach to the knees of the hind ones when the latter 

 are brought forwards. 



The brilliancy of the general hue having disappeared by immer- 

 sion in alcohol of the specimens collected, we are not prepared to 

 describe this accurately. As to the markings, they differ somewhat 

 from those of S. scalaris. The row of the large crescent spots 

 along the back is more compact, and not so distinctly bordered 

 with white. The yellowish band that runs from behind the eyes 

 backward to the middle of the tail is much broader ; and besides, 

 there is a second similar band extending from below the snout, and 

 passing under the eye and above the auditory aperture, to the in- 

 sertion of the hind locomotive limbs ; the sides, therefore, are not 

 ornamented with vertical, slightly undulating dark stripes ; the 

 irregular patches that are seen on that region are entirely deprived 

 of any white margin. The abdomen in the male is blue indigo, as 

 in most species of the same genus. The neck and throat are uni- 

 color in both sexes. 



This species inhabits the valley of the Great Salt Lake, where 

 it was collected by Captain Stansbury and Lieutenant Gunnison. 



