OPHIDIA. 163 



This, however, does not appear to amount to a specific difference. This Chameleon is found 

 in many parts of the Peninsula of India and in the northern parts of Ceylon ; it attains to 

 a length of 10 inches, the tail taking more than one-half. 



The occurrence of a second species of Chameleon in Indisi (Ch. ;pumilus, Latr.), mentioned 

 by Jerdon (I. c), is extremely doubtful. 



THE ORDER OF SNAKED— OPHIDIJ. 



Body exceedingly elongate, loithout limbs, or with merely rudiments of limbs, 

 scarcely visible from without ; the ribs are articulated moveably with the vertebral 

 column ; no sternum ; generally both jaws and the palate toothed ; the mandibles 

 united in front by an elastic ligament, and generally very extensible. Eyelids 

 none. Integuments with numerous scale-like folds, rarely tubercular. 



In the general remarks on the preceding Order, that of Saurians (p. 56), we have observed 

 that there is no sharp boundary-line between it and that of Snakes; we have mentioned 

 apparently limbless Saurians, of Ophidian appearance, but the systematic position of which 

 is decided by the structure of their jaws. On the other hand, certain Ophidians remind us, 

 by several characters, of the Saurian type ; we allude to the snakes forming the fii'st four 

 families {TypMopidce, Tortricidce, Xenopeltidce, TIropeltidce), which are distinguished by 

 polished, closely adherent, rounded, subequal scales, much resembling the smooth scales of 

 some Scincoids ; most of them have a very narrow mouth, unlike the enormous gape of 

 the typical Serpents, and some are without that longitudinal fold in the median line of the 

 chin which is so characteristic of Ophidians ; moreover, most have rudiments of the bones 

 of a pelvic arch. The reason why we adopt the view of those systematists who refer these 

 reptiles to the Ophidians, instead of associating them with the limbless Scincoids, is the 

 loose connexion of their jaw-bones, a character which must be considered as peculiar to the 

 Ophidians, and which is only somewhat less developed in the families mentioned than in the 

 typical forms. The two halves of the lower jaw in Ophidians, namely, are not united by an 

 osseous symphysis, but by an elastic ligament. The intermaxillary is but little developed, 

 generally without teeth, and coalesces with the nasal bones and the vomer into a single 

 moveable bone. The intermaxillary, palatine, and pterygoid bones are so loose that they 

 can not only be easily pressed outwards and forwards, but even the intermaxillary and man- 

 dibulary of one side can be moved in those du'ections independently of the bones of the other 

 side. The mandible is suspended from a much-elongated tympanic bone. 



This peculiar mobility of the jaw-bones enables the snakes to extend the gape in an 

 extraordinary degree, and to work their prey down through the collapsed pharynx. 



y2 



