.j02 snakes of CEYLON. 



Breeding.— All whose habits are known are viviparous, 



except Gatisus rhombeatus, Trimeresurvs mutus, T. monticola, 

 and Ancistrodon rhodostoma. 



Poison. — All are poisonous. Many are fatal to man, but 

 many others rarely, if ever, cause a fatal toxaemia. 



Lepidosis. — ^The head in some is covered with large shields 

 more or less after the Colubrine type. In others there are 

 only small scales. 



Gostals : Longer than broad ; all rectiform, or some obhque ; 

 smooth or keeled ; with or without apical facets. Vertebrals 

 not enlarged or feebly enlarged. Ventrals : Broad, three 

 times the breadth of the last costal row ; rounded or laterally 

 keeled. Anal : Entire. Subcaudals • Entire or divided. 



Dentition (for Indian species). — Maxilla : With a pair of 

 canaliculate fangs, and no other teeth. Palatine : Number 1 

 to 6 ; with or without edentulous spaces anteriorly and 

 posteriorly (completely edentulous in Trimeresurus jerdoni). 

 Pterygoid: Number 5 to 19; scaphiodont. Mandibular : 

 Number 10 to 19 ; scaphiodont. 



Distribution. — Europe, Asia, Africa, and America. 



There are thirteen genera arranged in two sub-families. 

 Five are represented in Indian limits, and of these four occur 

 in Ceylon. 



KEY TO THE SPECIES OF VIPERID^. 



(For Geylon Sixcies.) 



(A) Costals in 17 rows at midbody. A 



loreal pit. (See Figs. 96 and 97) . . Ancistrodon. 



(a) Slight boss on top of snout . . A. millardi. 



(b) A horn-like erect appendage on 



snout . . . . A. hypnale. 



(B) Costals in 19 rows at midbody. A 



loreal pit. (See Fig. 98) . . Trimeresurus tri- 



gonocephalus. 



(C) Costals in 29 to 31 rows at midbody. 



No loreal pit. (See Figs. 91 



and 93.) 



(a) Subcaudals divided . . Vipera russelli. 



(6) Sul)caudals entire .. EcMs carinatus . 



