CROCODILIANS. 289 



illary bones are slightly expanded at the insertion of this pair of 

 teeth. The first, fourth, eleventh and fifteenth pairs are the largest 

 teeth in the lower jaw, but the anterior tusks do not perforate the 

 intermaxillary . bones. 



In the foregoing gavial-like Crocodile the narrowing of the skull 

 to form the jaws is gradual, but in the true Gavials the cranium sud- 

 denly contracts into the prolonged upper jaw. In this subgenus 

 the two jaws together form a long, straight, narrow, and four-sided 

 column, with the angles rounded off, terminating in an expansion 

 something like that of the beak of the spoon-bill. The terminal 

 expansion of the upper jaw is indented by four vertical notches, 

 which receive the crowns of the first and second pairs of the in- 

 ferior teeth when the mouth is closed. The number of teeth is 

 always greater in the Gavials than in the Crocodiles or Alligators. 

 The formula of the common Gavial(l) (Gavialis gangeticus) is IJeI = 112. 

 The first five pairs of teeth above, are supported by the inter- 

 maxillary bones ; the first, third, and fourth teeth of the upper jaw, 

 and the first, second, and fourth of the lower jaw are the longest. 

 The eight or nine posterior teeth are nearly conical, the rest are 

 sub-compressed antero-posteriorly and present a trenchant edge 

 on the right and left side, between which a few faint longitudinal 

 ridges traverse the basal part of the enamelled crown. (2) The 

 position of the opposite sharp ridges and the direction of the flat- 

 tening of the crown are thus reversed in the Gavial and in the 

 extinct Crocodile {Croc, cultridens) , before-mentioned, which in other 

 respects most nearly resembles the Gavial in the form of the teeth. 



In most of the extinct species of Crocodilians, the teeth are 

 characterized by more numerous and strongly developed longitudinal 

 ridges upon the enamelled crown than in the recent species, and 

 they are commonly longer, more slender and sharper-pointed. But in 

 one of the Crocodiles with sub-biconcave vertebrae {Goniopholis crassi- 

 dens), from the Wealden formation and Purbeck limestone, the teeth 



(1) PI. 75a, fig. 3. This word ought to be written " Gharrial'' ; but the universal adoption 

 of the erroneous orthography in European scientific works, and its conversion into a Latin 

 generic name (^Gavialis", render an alteration undesirable. 



(2) Plate 75, fig. 2. 



U 



