REPTILES Ol<' THE I'ACFEIC COAST. 43 



SYNOPSIS OF GENERA. 



a. — A low dorsal crest composed of one longitudiual series of enlarged 



scales Dipsosaurus. — p. 43. 



a'^ — No dorsal crest. 



b. — Head without spines. 



c. — One or more well developed transverse gular folds. 



d. — Toes fringed laterally with prominent movable spines. 



Uma.— p. 46. 



d'^. — Toes without spines. 



e. — Supraiabials strongly imbricate; symphyseal plate smallei 

 than largest iiifralabial. 



f. — An ear-opening Callisaurus. — p. 47. 



f-. — No ear-opening Holbrookia. — p. 51. 



e'-'. — Supraiabials not imbricate; symphyseal plate not smaller than 

 largest infralabial. 



g. — No large interparietal plate; caudal scales small, not 

 strongly keeled nor sharply pointed, 

 h. — Ear without strong deuticulation and neck without 

 spinose tubercles; superciliaries imbricate; tail lon«,' 



and tapering Crotaphytus. — p. 53. 



h-. — Ear with strong denticulation and neck with numer- 

 ous spinose tubercles on lateral folds; superciliaries 

 not imbricate; tail scarcely longer than distance from 



snout to vent Sauromalus. — p. 60. 



g''. — A very large interparietal plate; caudal scales large, 

 strongly keeled, and sharply pointed. 



TJta.— p. 63. 



c'^. — No complete transverse gular fold Sceloporus. — p. 73. 



b'^ — Head with large spines posteriorly Phrynosoma. — p. 89. 



Genus 5. DIPSOSAURUS. 



Dipsosaurus, Hallow., Proc. Ac. Nat. Sci. Phila., 1854, p. 92 (type 

 dorsalis). 



The scales of the median dorsal row are slightly en- 

 larged, forming a small crest. The head is covered 

 with small convex subgranular plates. The dorsal and 

 caudal scales are small. There is one strong transverse 

 gular fold. Femoral pores are numerous. Males do 

 not have enlarged postanal plates. Digits each have a 

 series of keeled plates below. 



