62 3. IGUANIDJE 



dilated, except in the Central American Basiliscinae. Some 

 species of Sceloporus and Phrynosoma are ovoviviparous. 

 The iguanians of the area we are considering may be distin- 

 guished by the following: 



SYNOPSIS OF GENERA 



a. A dorsal crest composed of one longitudinal series of 

 enlarged scales. 



b. Tail with whorls of strong spinelike scales. 



. Ctenosaura. p, 64. 



b 2 . Tail without enlarged strongly spinose scales. 



Dipsosaurus. p. 71. 



a 2 . No dorsal crest, 

 bb. Head without spines. 



c. One or more well developed transverse gular 



folds; or a lateral fold between limbs, 

 d. Superciliaries not imbricate. 



Ear with strong denticulation and neck with 

 numerous spinose tubercles on lateral folds; size 

 very large; tail scarcely longer than distance from 

 snout to vent. 



Sauromalus. p. 84. 



d'. Superciliaries imbricate. 



e. Supralabials strongly imbricate; symphyseal 



plate smaller than largest infralabial. 

 f. Interparietal plate much smaller than ear- 

 opening; toes fringed laterally with prominent 

 movable spines. 



Uma. p. 131. 



f 2 . Interparietal plate larger than ear-opening; or 

 toes without later fringe of long spine-like 

 scales, 

 g. An ear-opening. 



Callisaurus. p. 138. 



