CTENOSA URA 67 



Ctenosaura consficuosa Dickerson, Bull. Amcr. Mus. Nat. Hist., Vol. 

 XLI, 1919, p. 461 (type locality, San Esteban Island, Gulf of 

 California, Mexico) ; Nelson, Mem. Nat. Acad. Sci., Vol. XVI, 

 1921, p. 171. 



Ctenosaura insulana Dickerson, Bull. Amer. Mus. Nat. Hist., Vol. XLI, 

 1919, p. 462 (type locality, Cerralvo Island, Gulf of 

 California, Mexico) ; Nelson, Mem. Nat. Acad. Sci., Vol. XVI, 

 1921, pp. 114, 115, 171. 



Description. — Body considerably compressed. Tail coni- 

 cal except at base, where almost square in sections. Limbs 

 and head large, latter sharply triangular and with flattened 

 top and almost vertical sides. Nostril large, in a round 

 plate whose posterior edge is nearer to orbit than to end of 

 snout. Rostral and symphyseal plates very broad and low. 

 Ten labials. A very large plate below the eyes; a series of 

 large superciliaries. Entire top and sides of head covered 

 with small, irregularly hexagonal plates, convex, except on 

 snout and lores. Ear opening very large, almost vertical, 

 and without denticulation. Several series of large sublabial 

 plates, passing gradually into the gulars. Dorsal crest begins 

 some distance behind shielded part of head, is composed of 

 high spines on nape, and gradually diminishes in height 

 posteriorly. It is continued on middle third or vertebral 

 line of the body as a series of enlarged flat plates, but is not 

 traceable on the posterior third. Back and sides covered with 

 small, smooth, subquadrate scales, which pass gradually into 

 larger ventrals. Gular regions covered with smooth scales, 

 which become gradually larger posteriorly. Smallest gulars 

 larger than dorsals, the largest smaller than ventrals. Scales 

 on limbs all smooth. Tail bearing whorls of spinose scales; 

 first three of these whorls separated from one another by 

 three series of smaller smooth scales; fourth, fifth and sixth 

 spiny whorls each preceded by two series of smooth scales, 

 and more distal whorls by single series which gradually 

 become spinose. 



