232 OPHIDIA. 



Some 55 species are known, arranged in three genera. About half 

 of the species occur in Madagascar and neighbouring islands, the 

 other half chiefly in Africa ; the common Chameleon is Mediterra- 

 nean ; a species inhabits Socotra, another South Arabia, and a third 

 India and Ceylon. 



Genus CHAMJELEON, 



Laurenti, Syn. Kept. p. 45, 1768. 



Claws simple ; scales on soles smooth. Tail at least as long as 

 the body. 



'2lo. Chamseleon calcaratus. 



Chauueleon calcaratus, Merrem, Tent. p. 102; liituleny. Cat. Liz. 



iii, p. 445, pi. xxxix, tig. 2. 

 Chamseleon zeylouicus (non Lmir.), Jcrduti, J. A. S, B. xxii, 185;>, 



p. 406. 

 Chamaeleon vulgaris (non Daud.}. Gilnth. Rept. S. I. p. 102 ; Thcoh. 



Cat. p. 120. 



Casque much elevated posteriorly, with strong curved parietal 

 crest ; the distance between the commissure of the mouth and the 

 extremity of the casque equals or nearly equals the distance between 

 the end of the snout and the hinder extremity of the mandible ; no 

 rostral appendages ; a strong lateral crest, not reaching the end of 

 the parietal crest ; an indication of a dermal occipital lobe on each 

 side, not reaching the parietal crest. No enlarged tubercles on the 

 body ; a feebly serrated dorsal crest ; a series of conical tubercles 

 form a very distinct crest along the throat and belly. Male with a 

 tarsal process or spur. Tail longer than head and body. Gular- 

 ventral crest white ; commissure of the mouth white. 



From snout to vent 7 inches ; tail 8. 



Hal. "Wooded districts of Peninsular India south of the Gangetic 

 plain, and Ceylon. 



Suborder III. OPHIDIA. 



The most characteristic peculiarity of Ophidians as compared to 

 Lacertians is the absence of solid union between the rami of the 

 mandible, the two halves being connected in front by an elastic 

 ligament ; a structure which allows the animal to dilate its mouth 

 and swallow a prey larger than the buccal orifice would otherwise 

 admit. In most Snakes (Boidce, Colubridce, Viperidw), the bones 

 of the upper jaw and' of the palate are likewise mobile, thus 

 allowing a dilatation of the gape to an extraordinary degree. There 

 are no movable eyelids : the lid extends as a transparent disk 

 over the eyeball, and its outer layer is cast off periodically in a 



