THORACOSAURUS. iT 
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 unossified spaces 
noticed in a somewhat similar position in the Deer among Mammals, and corre- 
sponding with the orifices represented as existing in the Zeleosaurus 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 parictal. 
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 skull, 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 macrorhynchus, are much larger than in the recent Gavial. They 
are oyoidal, 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 skull 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 
macrorhynchus, 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 tympanics, 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 maxille 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 macrorhynchus, as represented by the figures 
1 See Fig. 7, Plate XXV, of the Atlas to Pictet’s Traité de Paléontologie, 2d ed. 
