40 
EOCENE FISHES. 
the anterior vertebrae, both articular extremities are excavated on each side 
below the middle in correspondence with the lateral fossae, so as to produce 
a short T-shape. This excavation becomes less, and disappears on the pos¬ 
terior vertebrae. 
The scales are acute, and the gano'ine is entirely smooth. The two 
basal processes are of moderate length. The tube of the lateral line enters 
the posterior border, and issues on the inferior side of the scale at a point 
from two-fifths to one-third the length from the apex. 
In size, this species was similar to that of the Atractosteus ferox of the 
Mississippi. 
Four species of this genus have been described, and an additional one 
{Lepidosteus simplex, Leidy) figured. The former are the C. anax, Cope, 
C. cycliferus, Cope, in the Annual Report of the United States Geological 
Survey of the Territories of 1872, and C. atrox (Lepidosteus, Leidy) and 
C. notabilis {Lepidosteus, Leidy) in the Report of the United States Geo¬ 
logical Survey of the Territories, I, p. 189. The C. apanus differs from 
these in the following particulars: Its “posttemporal” bone is but one- 
fourth the size of that of C. anax, and is less profoundly sculptured; it 
has not the ganoid cranial ornamentation and rounded scales of the C. cycli¬ 
ferus. The articular faces of the vertebrae are more depressed than in the 
C. atrox, and are excavated on their inferior borders in a way not seen in 
that species. In an anterior dorsal of C. notabilis, the floor of the neural canal 
is convex at the border of the centrum, a character which does not belong 
to any of the vertebrae of the C. ayaniis. 
Thickness of a superior cranial bone. . . 0.005 
^ A lateral.. 0.015 
Diameter of basioccixntal cotylus.1 vertical ^ . . 0 ^ OXq 
I transverse. 0. 023 
Width of inferior basioccipital groove.. 0.007 
^ vertical (median).. 0. 011 
Diameter of second dorsal transverse. 0.018 
longitudinal. 0.010 
^ vertical.. 0.0135 
Diameter of anterior dorsaltransverse... 0.0155 
longitudinal. 0.014 
