292 FOSSIL REPTILES, 



smallness of thejugal. The pterygo'idean bones, greatly sepa- 

 rated from each other, have no teeth. 



The head of the cameleon is very singularly formed, still its 

 composition presents sufficient analogy to that of other lizards. 

 The casque of the occiput is supported by three ridges, one of 

 which appertains to the parietal, and the two others to the 

 temporal bones. In fact, it is that the parietal is very narrow, 

 and instead of sending branches to the temporal, it rises into a 

 point like a sabre, and the temporals also send similarly pointed 

 ridges or crests, which unite their points to that of the parietal. 

 There is but one principal frontal, bordered on each side by 

 the anterior and posterior frontals, above the orbit, the frame 

 of which cavity they unite together to form, and also to form 

 the sort of denticulated crest which the cameleon has in this 

 part. The rest of the bony orbit is formed by the lachrymal 

 and jugal, which last unites to the posterior frontal and 

 temporal bones. The muzzle is formed by the upper maxil- 

 laries, between which is a very small intermaxillary. 



The most extraordinary part of this arrangement is, that the 

 external nostrils are pierced in the maxillary bone, one on each 

 side, whose edge is somewhat completed above by the anterior 

 frontal. Still, on the muzzle, in the skeleton, are two fora- 

 mina, covered externally by the skin, and between which are 

 two very small nasal bones. The tympanic bone is cylindrical, 

 strait, and without concavity. Though the cameleon has no 

 external tympanum, there is, however, a tympanic cavity 

 tolerably large, closed on every side by muscles or bones, and 

 on the side of the mouth by a membrane which doubles that 

 of the palate, and is extended between the basilary and the 

 hinder point of the pterygoid. In this place, on each side, 

 is a narrow hole, which holds the place of the Eustachian tube. 



The lower jaw of lizards in general is composed of six 

 bones, like that of the crocodile and tortoise, but somewhat 

 differently disposed, and producing a form a little different. 

 This is principally occasioned by the coronoid apophysis being 



