218 FOSSIL REPTILES. 



side. The crocodile, like most reptiles, has six. These are 

 the dentary, in which are hollowed the alveoli of all the teeth. 

 The opercular J thus named by M. Adrian Camper, which covers 

 the entire internal face, except all in front, where it is formed 

 by the dentary. The angular and subangulart placed one above 

 the other, and extending to the hinder extremity of the jaw. 

 They leave a space between them in front occupied in its an^ 

 terior part by the end of the dentary, and afterwards by a large 

 oval foramen. Between the angular and opercular, on the 

 external face of the jaw, is another oval foramen smaller than 

 the last, and above it an empty space. The anterior point of 

 this space is bordered by a particular little bone, of a crescented 

 form> which the Baron names complementaire. 



The condyle, all the upper face of the posterior apophysis, 

 which gives an attachment to the digastric muscle, and all the 

 internal face of this part appertain to a special bone called by 

 M. Cuvier articulaire. 



Many interesting particulars may be remarked concerning 

 the teeth. Their number does not vary according to age. The 

 crocodile just broken from the egg has as many as the animal 

 of twenty feet in length. Their internal solid part is never 

 completely filled up, though, like other teeth, they are formed 

 by superposition of laminae. At whatever age the teeth of the 

 crocodile may be pulled out, there is found, either in the alve*- 

 olus, or in a cavity of the tooth itself, a small tooth in a greater 

 or less state of advancement, and ready to occupy the place 

 of the old one as soon as it shall have fallen. This succes- 

 sion would seem to take place many times, and to continue 

 during the life of the animal. Thus the teeth of the crocodile 

 are always observed to be fresh and pointed, and not more worn 

 in the old than in the young subject. The mode in which this 

 replacing of the teeth is performed is very curious. The teeth 

 of the crocodile being generally perfect cones widening towards 

 the root, could not fall out of their alveoli, whose entrance is 

 narrower than the bottom, but that the new tooth, as it develops, 



