THORACOSAURUS. 9 
length and corresponds with that part of the jaw just in advance of the divergence 
of the rami, and consists of portions of both dentals and splenials. The right dental 
contains remains of four alveoli with portions of their teeth, of which one incloses 
the entire crown of a successional tooth. 
This fossil fragment of the lower jaw I suspect to belong to the same species as 
the Vincenttown skull, but to a smaller or younger individual. The symphysis of 
the splenials, preserved at the posterior part, in the perfect condition, is estimated 
to have been about seven inches in length. The breadth of the jaw at the back 
extremity of the symphysis of the splenials is estimated to have been about four 
and a quarter inches; and at the fore extremity two and three-quarter inches. The 
oral surface of the splenials and dentals presents about the same degree of convexity 
as in the recent Gavial. 
The cabinet of the Academy contains a fragment of the left upper maxilla, 
apparently belonging to the same Gavial as the fossil skull just described, which is 
of especial interest from its retaining several entire and well-preserved teeth. The 
specimen, together with some small fragments of the jaw and teeth of the same 
individual, were obtained by Dr. J. L. Burtt, from the Cretaceous limestone, near 
Blackwoodtown, Camden County, N. J. The fragment to which we especially 
refer, represented in Fig. 2, Plate II, is about eight inches long, and corresponds 
with that portion of the left maxilla in the fossil skull which contains the back six 
teeth with the exception of the one or two last ones. It has a portion of the malar 
attached, and belonged to a rather larger individual than the Vincenttown skull, for 
it contains one tooth less in the space occupied by seven in the latter. 
The crowns of the teeth protruding from the specimen are curved conical as in 
the recent Gavial, but are more robust in proportion with their length. The ridges 
separating their outer and inner surfaces are also less prominent than in the living 
Gavial. The more anterior of the teeth, towards the base of the crown, internally 
exhibit a slightly fluted disposition. The enamel, which is jet black, is closely 
striated longitudinally with fine linear ridges, and also presents a feeble annular 
disposition towards the summits of the crowns. 
The measurements of the teeth, counting them from behind forward, are as 
follows :— 
Lines 
Length of crown of third tooth . 5 ; - : ; : ; : ». A 
Diameter of base from without inwardly . : : : : ; : . 5t 
Length of crown of fourth tooth ; : hes - ; : ; LO) 
Diameter of base from without inwardly. : : ° . ; : . 64 
Diameter of base at the divisional ridges . - - - c : : ee lt 
Length of crown of sixth tooth ; ; 4 : . : : . 133 
Diameter of base from without inwardly . : : 4 ; 5 A a Ae 
Diameter of base at the divisional ridges : - 2 : ’ 4 . OF 
Length of sixth tooth to bottom of aivedius : : : : : : > HS9 
‘Diameter of base of eighth tooth from without inwardly . é j : : 2 9% 
Diameter of base of eighth tooth at divisional ridges ; F : é “aL0 
A detached tooth, represented in Fig. 4, Plate I, from the same individual as the 
fossil fragment of jaw just described, presents the same characters as those contained 
in the latter. 
3 2 March, 1865, 
