3. CTENOSAURA 65 



Description*. Head elongate, flat above, muzzle nar- 

 rowed 5 nostril in the second third of the length to the orbit. 

 Three scales on canthus rostralis, each deeper than long. 

 Seven flat scales across muzzle between anterior angles of 

 orbits. Two rows between supraorbital series. Scales above 

 temporal muscles rather large, weakly keeled. Five series 

 of infralabial plates, not separated by 'smaller ones. Dorsal 

 crest rather elevated in adult, terminating at the rump. 

 Median caudal crest composed of conical scales, beginning 

 above the posterior margin of the femora. Tail cylindrical 

 at base, covered by whorls of prominent scales with conical 

 points which project strongly and which are separated by one 

 row of smaller flat scales on the upper half of the tail. On 

 the inferior side of the tail the whorl rows are separated by 

 two intervening rows, which are just like them, having a keel 

 and a mucronate apex. Beyond the middle of the length 

 (end lost) the tail is strongly compressed, but whether this 

 is due to shriveling on drying I am not sure. Median series 

 of spinous scales uninterrupted. The abdominal scales are 

 larger than the dorsal, which are longer than the lateral 

 scales 5 all are subquadrate, and none keeled. Seven femoral 

 pores. 



Color black, above and below. 



Distribution. The original specimens were secured at 

 Dondomuiguillo, Oaxaca, and Batopilas, Chihuahua, Mexico. 

 It has been stated that the range of this species includes the 

 extreme southern portion of Arizona, where one was 

 secured at Nogales. That this iguana really occurs naturally 



* Original description by Cope. 



