Caudal fin with a double notch; mouth crescent shaped; teeth subequal
in both jaws, oblique, serrate on both margins.
Galeocerdo falcatus, Ag.
_Corax falcatus_, Poiss. Foss., t. iii., p. 226.
This species is represented by a single tooth from the cretaceous
sandstone near the Garden of the Gods, Col. It does not agree
exactly with any descriptions or plates which we have seen; but
the differences are probably owing to the position or age of the
specimen. The crown is low, broad, and not very acute, the edge is
finely serrate, and there is no sensible difference between the
serrations of the two borders. The anterior border is undulating in
outline, but for the most part is convex; the posterior is short and
straight, and sends out quite a long heel. One face of the crown is
flat and the other is strongly convex. The root is stout and divided
into two fangs, which are longer and more distinct than is common in
this species. There are no denticles; cementum smooth.
_Measurements._
M.
Length of crown ·017
Depth of fang ·009
Height of crown ·011
Galeocerdo hartwellii, Cope.
Cret. Vert, p.. 244.
This species belongs to the group _G. Egertonii_, Ag., having the two
edges subequal and symmetrical. A single tooth from Cement Gulch,
Col.
_CESTRACIONTIDÆ._
"Two dorsal fins, an anal; nasal and buccal cavities confluent. Teeth
obtuse, several series being in function." (Günther.)
Ptychodus, Ag.
Poissons Fossiles, t. iii., p. 56.
Ptychodus Whippleyi, Marcou.
Geology of North America, 1858, p. 33.
Represented by a tooth from the cretaceous of Cement Gulch, almost
identical with the specimen described by Dr. Leidy from the
cretaceous of Texas. (Cont. to Ext. Vert. Fauna, p. 300.)