150 3. IGUANID& 



or less clouded with gray. The lower surface of the tail 

 is white with about eight (six to 10) cross-bars of intense 

 black. The belly is whitish. Males have a large blue patch, 

 marked with two oblique wedge-shaped black blotches, on 

 each side, which rarely are united ventrally. Some males 

 have a reddish or orange gular and postaxillary suffusion. 

 Females lack the lateral blue patch and have the lateroven- 

 tral dark blotches gray or obsolete. 



Length to anus. 60 65 65 66 66 67 



Length of tail 81 80 90 78 85 97 



Snout to back of inter- 

 parietal 11 12J4 11J4 12 12 12 



Snout to ear \2^/ 2 \Z l / 2 13 13 14- 13 



Width of head 11 11 10 11 11 12 



Fore limb 34 34- 35 36 33 37 



Hind limb ...._ 60 60 60 61 58 65 



Base of fifth to end of 



fourth toe ..... 24 24 24 24 23 26 



Distribution. Angel de la Guardia Island, Gulf of 

 California, Mexico. 



25. Callisaurus inusitatus Dickerson 

 SONORAN GRIDIRON-TAILED LIZARD 



? Callisaurus ventralis VAN DENBURGH, Proc. Acad. Nat. Sci. Phila., 



1897, p. 461. 

 Callisaurus inusitatus DICKERSON, Bull. Amer. Mus. Nat. Hist., Vol. XLI, 



1919, p. 465 (type locality, Tiburon Island, Gulf of California, 



Mexico). 



Description. Head rather short and low, with well 

 developed canthus rostralis. Nostrils large, opening on 

 upper surface of snout. Supraocular regions covered with 

 small or moderate sized plates and separated from each 

 other by one or two rows of plates. Upper head plates 

 (except interparietal) small and irregular, largest on frontal 

 and prefrontal regions, everywhere smooth and rather flat. 



