13. PHRYNOSOMA 429 



lip serrate. Gular region covered with small, smooth scales, 

 of which one series on each side is slightly enlarged. Below 

 fnfralabials a series of very large, spinose plates. Two or 

 three small groups of spines on sides of neck. Back, tail, 

 and upper surfaces of thighs bearing scattered, very slightly 

 elevated, weakly keeled, tubercular scales, with small keeled 

 scales or smooth granules between. Two or three series of 

 peripheral spines; those of the upper or of middle series 

 largest. Tail greatly flattened, and bearing a fringe of thickly 

 set, slender spines. Scales on front of arm large, pointed, 

 jnd strongly keeled. Those on chest small and smooth, ex- 

 cept anteriorly, where larger and keeled. Scales of abdomen 

 small and smooth. Most of lower caudal scales keeled. 

 Tympanum entirely covered with granular scales. Femoral 

 pores arranged in long series, seventeen to 23 on each side. 

 The body is ash-color or yellowish olive above, with a 

 narrow median dorsal line, of black or dark brown, extend- 

 ing from the occiput to the base of the tail. There is a 

 brown blotch on each side of the neck. Double series of 

 rounded dark spots ornament each side of the back, uniting 

 to form faint cross-bars on the tail. The lower surfaces 

 are silvery or yellowish white. 



Length to anus 43 



Length of tail 20 



Width of head 18 



Length of occipital 



spine 7^ 



Fore limb 22 



Hind limb 29 



Base of fifth to end of 



fourth toe._ 9 10 14 13 13 16 



Distribution. — The locality in Imperial County at which 

 the original specimen of this species was secured is stated as 

 the Great Desert of the Colorado, between Vallecito and 



