1922] Schmidt, Amphibians and Reptiles oj Lower California 631 



11. A pair of spurs just in front of the anal cleft, (representing the vestigial hind 



limbs) ; scales of top of head small Boidae. 



(a single genus in Lower California, Lichanura). 

 No spurs in front of anal cleft 12. 



12. A pair of large erectile fangs in the upper jaw Viperidae. 



(a single genus in Lower California, Crotalus). 



No erectile fangs in the upper jaw Colubridse. 



(see key below). 



Key to the Genera of Teiidae in Lower California 



Two frontoparietal plates Cnemidophorus. 



A single frontoparietal plate Verticaria. 



Key to the Genera of Iguanidse in Lower California 



1. A dorsal crest 2. 



No dorsal crest 3. 



2. Tail spinous at base Ctenosaura. 



Tail not spinous at base Dipso-saurus. 



3. Head with strong spines or horns Phrynosoma. 



Head without horns 4. 



4. Supraciliary scales juxtaposed; size large; form stout Sauromahis. 



Supraciliary scales strongly imbricate; form slender 5. 



5. Upper labials oblique, imbricate 6. 



Upper labials not oblique or imbricate 7. 



6. Back with an ocellated color pattern; two rows of subdigital scales; a series of 



very long lateral fringes on the digits JJma. 



Back without ocellation; a single row of subdigital scales; fringes present in 

 one species Callisaurus. 



7. Head covered with small irregular scales; no large occipital scale. . Crolaphytus. 

 Head scales enlarged, a large occipital 8. 



8. A well-defined collar, preceded by a transverse gular fold Uta. 



No collar 9. 



9. A well-defined transverse gular fold; body compressed; tail very long. .Sator. 

 No transverse gular fold; body usually depressed Sceloporus. 



Key to the Genera of Colubrine Snakes in Lower California 



1 . Scales keeled 2. 



Scales smooth 4. 



2. The two prefrontal plates longitudinally divided, forming four prefrontals. 



Pituophis. 

 Only two prefrontal plates 3. 



3. Anal plate simple Thamnophis. 



Anal plate divided Natrix. 



4. Anal entire 5. 



Anal divided 8. 



5. Loreal scales 2-4; rostral projecting Phyllorhynchus. 



One loreal; rostral not projecting 6. 



