94 3. IGUANID& 



somewhat enlarged, feebly spinose. Scales on back and 

 sides small, largest medially and on strong lateral fold, 

 smooth and juxtaposed except laterally, becoming there 

 tubercular or keeled and slightly mucronate. Dorsals 

 averaging 30 to a head-length. Ventral (scales smooth, 

 smaller than dorsals, about 1 54 to 1 63 rows between gular 

 fold and anus. Tail little longer than head and body, 

 conical, very stout, and covered with whorls of small, 

 smooth or weakly keeled, feebly spinose scales j about 63 

 to 65 scales in a whorl -at largest part of tail. Scales on 

 arm, forearm and lower leg somewhat larger and more 

 strongly keeled than in S. ater. Femoral pores very large 

 in males, small in females, varying in number from twelve 

 to seventeen j average 14.13. 



The head, neck, and limbs are pale yellowish olive or 

 dull brownish black, with scattered scales of grayish yellow. 

 The back is yellowish olive, or a dull straw-color, speckled 

 or suffused with dark reddish brown or black and sometimes 

 crossed by broad bands of dark brown or black. The tail 

 is dull straw-color with or without wide rings of olive or 

 yellowish brown. The ventral surfaces are dull yellow, 

 suffused in the male with brownish olive on the limbs, chest, 

 gular region and chin, and more or less speckled with dark 

 brown or black. 



Length to anus 148 150 166 



Length of tail 149 142 



Snout to orbit 11 11 



Snout to ear 27 30 



Width of head 24 28 36 



Fore limb 60 60 



Hind limb 87 86 100 



Base of fifth to end of fourth toe 27 27 34 



Distribution. This species is known only from Tiburon 

 Island, Gulf of California, Mexico, but the chuckwalla re- 



