6 THORACOSAURUS. 



fossil head about three and a-half feet in length. If we allow as many vertebras 

 to the New Jersey Gavial as are possessed by the existing species, or the same pro- 

 portionate length of body to the head, the former animal in its entire condition 

 would measure twenty feet in. length. 



The upper view of the fossil skull, represented in Fig. 1, Plate I, bears a strong 

 resemblance to that of the living Gavial, except that the boundaries of "the orbits 

 are not conspicuously everted as in the latter, and the muzzle is not so abruptly 

 narrowed forward. In the characters just mentioned the fossil appears intermediate 

 to the Gavial and Mecisto])s, and resembles the Teleosauri of the Liassic formations 

 of Europe, but most closely the Cretaceous Gavialis macrorhynclius. The posterior 

 and lateral outlines of the cranium are the same in both the New Jersey and living 

 Gavials, as is also the form of the large temporal foramina. The space separating 

 the latter in our fossil, formed by the symmetrical parietal, is both relatively and 

 absolutely narrower than in the living Gavial. The forehead, as formed by the 

 frontal and pre-frontals, has almost the same proportionate breadth as in the latter, 

 but is only slightly concave in consequence of the non-eversion of the orbital 

 borders. The frontal in the fossU, as is also the case in the Gavialis maxirorJiynchus, 

 is prolonged considerably more posteriorly to join the parietal than in the recent 

 Gavial or Mecistops. The orifices of the orbits, when perfect, appear to have had 

 nearly the same proportionate size and form as in the living Gavial, but their borders 

 in no position are everted, not even so much as in Mecistops^ or the Alligator, A. 

 Mississipiensis. 



The post-frontals, separating the orbits from the temporal foramina, arc propor- 

 tionately narrower than in the recent Gavial ; while the post-orbital arches, formed 

 through conjunction of the post-frontals with the malars, are broader. 



As in the extinct Gavialis macroyhynchus, the face in advance of the forehead 

 and orbits in the New Jersey fossil slopes with a gentle curve forward to the broken 

 end of the muzzle. 



The malar and lachrymal are more prolonged upon the face or muzzle than in the 

 recent Gavial. Thus in the latter, the anterior border of the malar reaches as far 

 forward as the position of the fourth tooth, counting from behind, and the lachrymal 

 advances as far as the sixth tooth. In the fossil the malar extends as far forward 

 as the seventh tooth, and the lachrymal reaches beyond the position of the ninth 

 tooth. 



The posterior extremities of the nasals are angular, and extend back on a line 

 with the anterior orbital margins. They widen forward to the anterior ends of ih.e 

 pre-frontals, then very gradually narrow forward a short distance beyond the lach- 

 rymals, and finally narrow abruptly into a pair of linear prolongations extending to 

 the broken end of the fossil. A similar condition of the nasal bones is observed to 

 exist in the Gavialis maerorhynchus. 



The surface of the cranium, as formed by the parietal, mastoids, frontals, pre- 

 and post-frontals, is less foveated than in the full-grown Gavial of the Ganges ; and 

 the surface of the muzzle is likewise rather less roughened, though perforated by 

 as many vasculo-neural foramina. 



On both sides of the face, in the fossil, there is a large hole, situated between 



