50 SQUAMATA 



dd*. Plates on top of head not larger than those on 

 body 5 anus bordered in front by a single plate j 

 a small spine at end of tail. 



Leptotyphlopidae. p. 624. 



cc*. Ventral plates more than twice as broad as dorsal 

 scales. 



ddd. No rattle at end of tail 5 no pit between nostril 

 and eye. 



ee. A small spur at each side of the anus 5 tail 

 short and truncate ; or top of head with 

 small scales 5 pupil vertical. 



Boidae. p. 630. 



ee". No spur at side of anus; tail tapering j top 

 of head with large plates 5 pupil round or 

 vertical. 



ff. No enlarged fangs at front of mouth j 

 coloration, if in rings, not red separated 

 from black by white (yellow). 

 Colubridae. p. 64-4. 



f f ". A pair of large, permanently erect fangs 

 near front of upper jaw; coloration, in 

 rings, red separated from black by white 

 (yellow) . 



Elapidae. p. 887. 



ddd 2 . A horny rattle at end of tail; a pit between 

 nostril and eye; a pair of large erectile fangs; 

 pupils vertical, 



Crotalidae. p. 893. 



bb*. Tail short, strongly compressed laterally, paddle- 

 shaped. 



Hydridae. p. 891. 



