THORACOSAURUS. 7 



the lachrymals and pre-frontals, a short distance in advance of the inner part of the 

 orbits, which, though perhaps accidental, reminds one of the uuossified spaces 

 noticed in a somewhat similar position in the Deer among Mammals, and corre- 

 sponding with the orifices represented as existing in the Teleosaurus or Pelago- 

 saurus typus^ between the lachrymals and nasals. 



The lateral view of the fossil skull, represented in Fig. 2, Plate I, is nearly re- 

 peated by that of the corresponding portion of the skull of the recent Gavial, except 

 that the face in the former presents a more gradual slope from the position of the orbit. 



The occipital view of the fossil also bears a near resemblance to that of the recent 

 Gavial ; its upper outline, however, is more nearly horizontal, and is not prominent 

 at the middle. The supra-occipital is much broader in relation with its height than 

 in the recent Gavial, or the Alligator. Its upper extremity forms a square plate, 

 with everted edges, over an inch in breadth, articulating by transverse suture on the 

 top of -the cranium with the parietal. 



The exoccipitals, the occipital condyle, and the occipital foramen present nothing 

 peculiar. The latter is an inch and a half in breadth and ten lines in height. 



The inferior view of the fossil skidl, represented in Fig. 1, Plate II, though pre- 

 senting the same general outline of form and construction as in the recent Gavial, 

 nevertheless exhibits a number of important peculiarities. The palatine foramina, 

 as in Gavialis macrorhynclms, are much larger than in the recent Gavial. They 

 are ovoidal, with their narrow extremity forward and their inner sides nearly 

 parallel. They extend from the ento-pterygoids as far forward as the position of 

 the seventh tooth, counting from behind. The part of the skuU corresponding with 

 the position of the foramina and the intervening palatines rises even more than in 

 Mecistops. The anterior extremities of the palatines reach as far forward as the 

 position of the ninth tooth from behind. In advance of the palatines the surface 

 of the muzzle is flat. 



Neither the palatines nor the ento-pterygoids present capsular osseous dilatations, 

 such as exist in the recent Gavial. 



The posterior nares are large, and, as in the Alligator and the extinct Gavialis 

 macrorhynchits, are divided by an osseous septum of the ento-pterygoids. The 

 lower border of this septum forms a stout ridge expanding behind upon the basi- 

 sphenoidal. The latter includes a large, transversely oval pit, communicating with 

 a canal piercing the bone as in other Crocodilians. 



The under surface of the tympanies, as observed in this view of the skull, exhibits 

 a deep and wide gutter or concave fossa, of which only a superficial trace is present 

 in the recent Gavial. 



The remaining portions of the maxillee in the fossil, on each side, contain the 

 sockets and portions of the fangs of fourteen teeth, occupying a space sixteen and 

 a half inches in length. 



Compared with the skull of Gavialis onacrorhynchus, as represented by the figures 



* See Fig. T, Plate XXV, of the Atlas to Pictet's Traite de Paleontologie, 2d ed. 



