Fossil Gavial from New Jersey. 159 



the replacing tooth either within the old one or in a rudimen- 

 tary form, or at the bottom of the socket. Among the loose 

 fragments, to which I regret being unable to assign its proper 

 place, but which is near the bottom of a socket, is a small 

 replacing tooth, '25 in length. It is of a conical form, and 

 blunt at its summit. See fig. 8. It is worthy of remark, that 

 this tooth, instead of originating from the centre of the bottom 

 of the socket, lies near the inferior and anterior side. Are we 

 authorized to infer, that the individual species under exami- 

 nation belonged not to an adult animal, but to one which had 

 not yet attained its full growth, and that the position of this re- 

 placing tooth indicates that the outer edge of the alveole would 

 be advanced farther with the growth of the animal ? According 

 to Cuvier, the replacing tooth generally commences near the 

 inner surface ; and hence it is on this side, by its compression, 

 that the old tooth frequently exhibits, near the upper edge of 

 the alveole, a notch or indentation on its inner side, proving 

 that absorption has taken place. 



The sockets and parts of sockets are '8 apart on the supe- 

 rior surface of this dental bone, and approach nearer at their 

 bases. The central socket contains the most perfect tooth in 

 all the fragments. Fig. 7 represents its appearance, describing 

 a segment of a circle whose diameter is four inches. The 

 whole length of the tooth is 2-6. The direction of this curve 

 is forward and outwardly ; or, in other words, its lower extre- 

 mity is near the internal plane of the dental bone, while the 

 external portion of the tooth is not far from the outer edge 

 of the same bone. Within the socket the tooth is cylindrical, 

 and, as is common among animals of this class, it is larger than 

 the exposed portion. It is hollow, and filled with the soil in 

 which it was found. The upper part of the tooth Is much in- 

 jured, but enough remains to enable us to describe its general 

 form, which is conical, recurved, and rather broader in the 

 transverse axis of its base than in the longitudinal direction of 

 the dental bone. A very minute portion is all that is left of its 

 external coat; but from this we may state, that it is of a brown 



Vol. III. 21 



