288 CROCODILIANS. 



The fourth or great tooth below does not pierce the upper jaw 

 in this species. 



Alligator trigonatus,{\) 2^5=82 4;5 ;^'Jti2 =largest. 



Alligator niger, It^-^g^T^ txitIt2= largest. 



In almost all, if not all of these species of Alligator from eight to 

 ten of the posterior teeth are straight, sub-compressed, and terminated 

 by an obtuse mammilloid crown. 



Crocodilus rhomhifer, j5Er5=64 J-,J;=largest. 



Crocodilus Gravesii, 1|Eib=66 4,'y,'iS;i'i| =largest. This species ex- 

 hibits, besides the notch for the fourth lower tooth or canine, a 

 remarkable emargination for the elongated crowns of the ninth, tenth, 

 and eleventh teeth. 



Crocodilus vulgaris, 11^=66 i;|7if;=largest. 



^ Ti ■•• , 18— 18, or 19— 19 ^^ ^o 2,3,8,9 , . 



Crocodilus oiporcatus, 151^5 — 00 or 00 174 — - — largest. 



Crocodilus acutus, JfEfs =^^ 4'-^'=largest. In this species the 

 first ten teeth, counting from the anterior part of each side of both 

 jaws are pointed and slightly recurved : the rest are straight and 

 obtusely conical. 



Crocodilus intermedius. The name of this species indicates the 

 gradational character between the Crocodiles and the Gavials, which 

 it manifests in the increase of the longitudinal over the transverse 

 diameter of the cranium and in the comparative slenderness of its 

 jaws : the alveolar border is less deeply sinuous in both jaws, and 

 the rami of the lower jaw are united along the anterior fourth part of 

 their length. The teeth are relatively smaller than in the preceding 

 Crocodiles ; the dental formula is 11=11=66 1717^"= largest. 



The transition, of which the first steps were made by the Croco- 

 dili acutus and intermedius is completed by the Gavialis Schlegelii, in 

 which the head is more elongated and contracted, the teeth smaller 

 and more equal, and the anterior pair of the lower jaw received, like 

 the fourth pair, in notches at the outside of the intermaxillary bone, 

 between the first and second teeth of the upper jaw. 



The first, second, third and ninth teeth of the upper jaw, are 

 larger than the rest, the ninth is the largest, and the superior max- 



(l) Champsa irigonata Natterer. 



