SNAKES 253 



(Subcaudal shields in two rows, at any rate in 



6 j the posterior part of the tail Pseudechis. 



iSubcaudal shields in a single row 7 



I Scales disposed very obliquely Notechis. 



' (Scales not remarkably oblique Denisonia. 



IV. AMERICAN ELAPIN^E. 



The American Elapines all belong to the one genus, Elaps, which 

 is restricted to America and includes about thirty species. 



The species of Elaps are generally brilliantly coloured, in rings. 

 The maxilla is very short and has no teeth but the large poison-fangs. 

 The head and eye are small, and there is no distinct neck. There is 

 no loreal shield. The scales are smooth and number fifteen in a 

 transverse row. The tail is short and the sub-caudal shields are in 

 two rows in all or part of its extent. 



B. SYNOPSIS OF VIPERID^E. 



A sensory pit (loreal pit) between the eye and 



the nostril (fig. 105, /) Crotalince. 



No loreal pit Viperince. 



(a) SYNOPSIS OF GENERA OF VIPERIN/E. 



Crown of the head with large symmetrical shields 



like a Colubrine (cp. fig. 104,1) i 



Crown of the head with small scales only, or 



with small scales and some small shields 2 



(Numerous teeth in the mandible ; loreal shield 

 present 3 

 Only two or three teeth in the mandible : no 

 loreal shield (fig. 107) Atractaspis. 

 (Africa, Arabia and Persia.) 



/Tupil round ; scales on the sides of the body very 



oblique Causus. 



3 \ (Africa.) 



Lateral scales not particularly oblique Azemiops. 



\ (Upper Burma.) 



(Scales on the sides not smaller than those on 

 the backs, their keels sharp, i.e., not serrated 

 (cp. fig. 102, *,/) 4 

 Scales on the sides smaller than those on the back 5 



[Ventral shields of the ordinary curved form 6 



4 j Ventral shields with a keel on either side Eristicophis. 



(Baluchistan.) 



'Nasal shield either touching the rostral shield 



or separated by a naso-rostral shield Vipera. 



6 { (Europe, Asia and Africa.) 



Nasal shield separated from the rostral shield 



by small scales (fig. 104, K) 7 



