MESOZOIC VERTEBEATA. 
29 
locality, not far distant, were found numerous remains of Saurian bones, 
embracing dermal and cranial pieces, coprolites, a fragmentary tooth, &c., 
which may have some affinity to these. The species indicated by the former 
has been described and named as follows: 
TYPOTHORAX, Cope. 
Proc. Acad. Phila., 1875, p. 265; Ann. Report Chief of Engineers, 1875, p. 1004. 
The fragment of jaw belonging to this genus is probably maxillary in 
position, for the following reasons: The interior face of the bone is sutural, 
and for the most part solid. This would refer it to the position of the sym- 
physeal portion of the dentary bone of a gavial-like form, but for other con¬ 
siderations. Supposing the piece to be dentary, and the suture therefore 
vertical, the incongruity follows that the alveolar face becomes very steep, 
so much so as to prevent the interlocking of tlie teeth, which become lateral 
in position. If, however, the jaw fragment be reversed in position, and the 
alveolar face placed in a horizontal position, the suture of the inner side 
forms a sharp angle with the vertical plane, as it should on the supposition 
of its being the maxillary bone. The wedge-shaped section necessary to 
fill the space between it and the median plane will then be that of the pro¬ 
longed posterior spine of the premaxillary bone. The solidity of this por¬ 
tion of the muzzle is inconsistent with the gavial genera of the Jura and 
later times, but not with the structure of the Triassic Belodons. The pos¬ 
terior part of the inner face is, however, strongly excavated, and the sutural 
margin exhibits an outward deflection, which is either the boundary of the 
nostril or the suture for the apex of the prefrontal or nasal bone. In either 
case, the nasal cavity and the nostril are posterior in position in conformity 
with the structure of the “Thecodont” Crocodilia. The alveoli are large 
and arranged in a curved line, one of them somewhat exterior in position 
and isolated by a short diastema like a canine. Surface of the bone pitted. 
The dermal scuta found close to the jaw fragment have a flat upper surface 
marked with shallow pits rather closely placed, having resemblance to an 
obsolete Trionyx sculpture. Near one of the margins of the bone, the^pits 
run out in shallow grooves. A portion of a vertebral centrum found with 
the jaw exhibits one articular face; this is shallow, concave, of the type of 
