CROCODILIANS.

289

illary bones are slightly expanded at the insertion of this pair ofteeth. The first, fourth, eleventh and fifteenth pairs are the largestteeth in the lower jaw, but the anterior tusks do not perforate theintermaxillary bones.

In the foregoing gavial-like Crocodile the narrowing of the skullto form the jaws is gradual, but in the true Gavials the cranium sud-denly contracts into the prolonged upper jaw. In this subgenusthe two jaws together form a long, straight, narrow, and four-sidedcolumn, with the angles rounded off, terminating in an expansionsomething like that of the beak of the spoon-bill. The terminalexpansion 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 isalways greater in the Gavials than in the Crocodiles or Alligators.The formula of the common Gavial(l) (Gavialis gangeticus) is = 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 aresub-compressed antero-posteriorly and present a trenchant edgeon the right and left side, between which a few faint longitudinalridges traverse the basal part of the enamelled crown. (2) Theposition of the opposite sharp ridges and the direction of the flat-tening of the crown are thus reversed in the Gavial and in theextinct Crocodile (Croc, cultridens ), before-mentioned, w T hich in otherrespects most nearly resembles the Gavial in the form of the teeth.

In most of the extinct species of Crocodilians , the teeth arecharacterized by more numerous and strongly developed longitudinalridges upon the enamelled crown than in the recent species, andthey are commonly longer, more slender and sharper-pointed. But inone of the Crocodiles with sub-biconcave vertebrae (Goniopholis crassi- .dens), from the Wealden formation and Purbeck limestone, the teeth

(1) PI. 75 a, fig. 3. This word ought to be written “ GharriaT’ j but the universal adoptionof 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.

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