286 CROCODILIANS. 



hundred teeth ; Abuhamed was more reasonable and allowed 

 eighty. (1) 



How many teeth a crocodile may develope through the whole 

 course of its life in uninterrupted succession will never perhaps be 

 determined ; they, then, would doubtless far exceed in number the 

 liberal allowance of Tatius ; but with regard to those teeth which 

 are in use in the jaws at any given time the number is now well 

 established, e. g. the Crocodile of the Nile has 5|eS = 68 ; that of 

 the West Indies {Crocodilus acutus) has |^ = 66 ; the common 

 Alligator (Alligator luciusj has if^g = 76. The great Gavial or 

 G^Lrrhial rGavialis gangeticusj has f^l = J 18. Thus the different 

 species and genera of Crocodiles differ from each other in the num- 

 ber of teeth, and also the individuals differ within small limits, as 

 will be presently shown. 



The best and most readily recognizable characters by which the 

 existing Crocodilians are grouped in appropriate genera are derived 

 from modifications of the dental system. 



In the Caimans, (Genus Alligator), the teeth vary in number 

 from ^i^s to §3: the fourth tooth of the lower jaw, or canine, is 

 received into a cavity of the palatal surface of the upper jaw, wh^e 

 it is concealed, when the mouth is shut ; in old individuals the upper 

 jaw is perforated by these large inferior canines, and the fossae are 

 converted into foramina. 



In the Crocodiles, (Genus Crocodilus), the first tooth in the 

 lower jaw perforates the palatal process of the intermaxillary bone 

 when the mouth is closed ; the fourth tooth in the lower jaw is received 

 into a notch excavated in the side of the alveolar border of the upper 

 jaw, and is visible externally when the mouth is closed. 



In the two preceding genera the alveolar borders of the jaws 

 have an uneven or wavy contour and the teeth are of unequal size. 



In the Gavials, (Genus Gavialis), the teeth are nearly equal in 

 size and similar in form in both jaws, and the first as well as the 

 fourth tooth in the lower jaw, passes into a groove in the margin 

 of the upper jaw, when the mouth is closed. 



In an extinct species, the * Crocodile d'Argenton ' of Cuvier,(2) 



(1) These authors are quoted by Tiedemann and Oppel in their Naturgeschichte der Am- 

 phibien, fol. 1817, p. 39. (2) Ossem. Fossiles, 8vo. 1836, torn, ix, p. 330. 



