138 Fossil Reptiles of New-Jersci/. 



2. Of the Geosaurus. PI. III. fisrs. 3 and 4. 



'to'- 



This subgenus appears to us well established upon another 

 ossil tooth with a small fragment of attached jaw, from the 

 same locality with the preceding. As far as we are acquainted 

 it has hitherto been unnoticed, and the following description is 

 offered in confirmation of our opinion. 



The tooth is compressed, pyramidal, curved backwards, with 

 sharp edges dividing it anteriorly and posteriorly into two sur- 

 faces. The posterior edge is the most acute. Both of these 

 surfaces are subdivided mto four or five facets, which are 

 however, so indistinct as to be visible only when held in a cer- 

 tain position. The sharp edges are not manifestly serrated, 

 but by the aid of a lens, there are indications of a serrature 

 towards the base. The whole tooth is covered with a smooth 

 jet black shining enamel, except at the apex, where it has been 

 worn by use. The osseous support presents nothing peculiar, 

 being similar in shape, color, and structure to the preceding. 



The following are the principal dimensions. 



Length of tooth, .... 0*09 



Width at base, . . . . 0*07 



Do. transversely, . . . . 0*45 



Distance of base of tooth from upper end of jaw, 0*06 



From various considerations we should be disposed to place 

 this tooth among the most anterior of the lower jaw, but 

 postponing the consideration of this matter until more perfect 

 specimens shall be found, let us examine what relation the ani- 

 mal to which this tooth belonged bears to other fossil marine 

 reptiles. The elevated position of this tooth on its osseous 

 support places it in the groupe composed of Mosaurus and 

 Geosaurus, while its compressed shape removes it from the 

 former, and its indistinctly serrated edges might cause some 

 hesitation in arranging it with the latter. In describing the 

 subgenus Geosaurus, Cuvier appears to attach much import- 



