1.;:, 



A* the teeth of the Croeottitim are shed and renewed many times ui the count of Hie. but 

 always in the vertical direction, or in that according to which the human deciduous teeth are 

 directly replaced, the number of the teeth i* the sajne in thr young Crocodile when it quid 

 the egg M when it hat attained its full growth : it doe* not appear, at least, that there arc- 

 any teeth added to the serie* from behind forward* without displacing previous teeth, or 



which can be compared with the true molar* in Mammalia. 



llu*tcrian. 



7.") I Two of the larger-sized teeth, with the germ of a successional tooth, of a Cro- 

 codile (Crocodile biporcatiui). 



The conical enameled crown i* lea* acute than in the Canal, and it* transverse section in 

 circular ; but it present* two opposite trenchant ridge*. In the older and more worn of tlu-M- 

 two teeth the walls of the long hollow fang have not been attacked by the absorbent prorew, 

 which would indicate that the succession of the teeth was lea* frequent and rapid than in the 

 Garni. 



HuMtfria*. 



755. A tooth of a younger Crocodile, with the crown transversely bisected and the 



base deeply notched by the absorbent action. Hnntrriat>. 



756. The tooth of a Crocodile, with part of the enamel removed from the crown, 



showing its thickness. Presented by Sir Everard Home, Bart., F.K.S. 



757. Two of the posterior teeth of a Crocodile, in wluch the crown is shorter in pro- 



|K)rtion to the base, and is more compressed, than in thr anterior teeth. 



Ilunterian. 



758. Four nuchal scutes of the epidermal covering of the Crocodilwi biporcat**. 



MK*. Brit. 



?.~>9. A similar specimen from a larger individual of the Crocodil** biporcatiu. 



Mtu. Brit. 

 760. A skeleton of a young Alligator (Alligator lurittx). 



The character of the genus is marked by the reception of the crown of the fourth tooth, or 

 ranine, of the under jaw in a deep fossa at the outer part of the palatine suture, between thr 

 maxillary and pmnaxillary bone*, by which these teeth are concealed when the mouth is shut. 

 Both maxillary and premaxillary portions of the skull are unusually broad in proportion to 

 their length, but this i* a character of the specie* rather than the genus. The nasal bone* 

 end their attenuated extremities forward* to the premaxillaries so a* to diride the anterior 

 external nostrils into two carities. Cuvier figure* the same peculiarity in the Alligator lumu 



