3 



250 TROPICAL MEDICINE AND HYGIENE 



as the succeeding tables, is based upon those published in 

 Mr. G. A. Boulenger's classical " Catalogue of Snakes 

 in .the British Museum." 



SYNOPSIS OF FAMILIES OF SNAKES. 



Body covered in every part with hard, shiny, 

 imbricating, "cycloid" scales of uniform 

 size ; eyes minute, lying beneath the head- 

 shields ; coronoid present ; no transpalatine 

 or squamosal bones. Worm-like snakes, 

 living underground 2 



Scales and eyes normal ; transpalatine bone 

 present (cp. figs. 95 and 96, tr.) 3 



[ Maxilla transverse, with a few teeth ; mandible 



toothless Typhlopidce. 



1 Maxilla toothless ; mandible with teeth Glauconiidce. 



Coronoid bone present (fig. 97, cor.} ; ventral 



shields either of moderate size or quite small 4 



Coronoid bone absent ; ventral shields, except 



in some aquatic species, large 5 



fNo squamosal bone; ventral shields small. 

 Burrowing snakes restricted to the hills of 



Peninsular India and Ceylon Uropeltidce. 



Squamosal bone present (cp. fig. 95, sq.) ; 

 concealed vestiges of hind-limbs present 6 



Squamosal large ; ventral shields usually of 



fair size Boiidce. 



, Squamosal small ; ventral shields extremely 



small Ilysiida. 



(S.E. Asia and Tropical S. America.) 



I Maxilla horizontal 7 



' 1 Maxilla short, not horizontal, vertically erectile Viperidcc. 



f Pterygoid bone reaching quadrate or mandible 



(fig. 95, pt.}\ a mental groove (fig. 94, w..) 8 



\ Pterygoid bone not reaching quadrate or 



mandible; no mental groove A mbly cephalitis. 



(S.E. Asia and Tropical S. America.) 



Teeth in premaxilla ; ventral shields not ex- 

 tending completely across the belly Xenopeltida. 



(S.E. Asia.) 



No teeth in premaxilla (fig, 96, p.m.} ; ventral 

 shields stretching right across the belly in 

 almost all the species that live on land Colubridce. 



(i) None of the maxillary teeth 



grooved (harmless) Aglypha. 



(ii) Some of the posterior maxillary 



v 



I: 



I 



Colubridce 



teeth enlarged and grooved (sus- 

 picious) Opisthoglypha. 



(iii) Front tooth in the maxilla en- 

 larged and canaliculate (venomous) Proteroglypha. 



