Vertebræ D. 12, C. 18, Radii D. 14, A. 8, V. 8, C. 41, P. 5 only
visible, not all preserved. The dorsal fin is long, and projects
beyond the beginning of the anal fin; the mouth is terminal, and
the muzzle rather sharp. All the bones of the skeleton are very
slender; and this is especially true of the ribs, which are not as
thick as the interneurals. The neural and hæmal spines are short
and slender. The origin of the dorsal is nearer to the muzzle than
to the caudal; though, as a whole, the fin is on the hinder half of
the body. There are no interneural spines in front of the dorsal
fin; those supporting the fin are short, slender, and without the
laminar expansions found in _T. foliarum_. The caudal fin consists of
numerous jointed rays, which are supported by the neural and hæmal
spines of the last three vertebræ. The scales are small, and exhibit
the peculiarities of the genus, but the rows are too imperfect to be
counted.
_Measurements._
M.
Total length (straight) ·0935
Length of head ·018
Length of vertebral column ·055
Length of caudal fin ·024
Length of dorsal spine ·011
Length of anal spine ·009
Depth of head posteriorly ·016
Length of mandibular ramus ·010
Length to dorsal fin (from muzzle) ·033
Length of dorsal fin ·0135
Depth of body at middle of dorsal fin ·017
Found in the insect beds at Florissant, Col.
_CATOSTOMIDÆ._
Body covered with scales; head naked; margin of upper jaw formed by
the premaxillaries; mouth toothless. Pharyngeal teeth in a single
series, and exceedingly numerous and closely set. Dorsal fin elongate
and opposite the ventrals. Anal short, or of moderate length.
AMYZON, Cope.
U. S. Geolog. Survey of the Terrs., 1872, p. 642.
Allied to _Bubalichthys_. Dorsal fin elongate, with a few fulcral
spines in front. There are three broad branchiostegals. The vertebræ
are short, and the hæmal spines of the caudal fin are distinct and
rather narrow. The teeth are arranged comb-like, are truncate,
and number from thirty to forty. The dentary bone is slender and
toothless, and the angular is distinct.
Amyzon commune, Cope.
U. S. Geolog. Survey of Terrs., 1873, p.
Represented by several fine specimens from near Castello's Ranch, Col.
_SAURODONTIDÆ._
For a very complete definition of this family, see Cope's Cretac.
Vert., p. 183.
PORTHEUS, Cope.
Cretac. Vert., p. 189 et seq.
"Teeth subcylindric, without serrate or cutting edges, occupying
the maxillary, premaxillary, and dentary bones; size, irregular;
premaxillary, median maxillary, and dentary much reduced. No foramina
on inner face of jaws. Teeth on the premaxillary reduced in number.
Opercular and pre-opercular bones very thin. Cranial bones not
sculptured."
Portheus thaumas (?), Cope.
Loc. cit. p. 196.
Maxillary large, teeth three; third mandibular small, without cross
groove in front of it.
A single tooth from the cretaceous sandstone of Cement Gulch, Col.,
is provisionally referred to this species; the reference cannot be
certain, as the specimens described and figured by Professor Cope
have the crowns of the teeth broken. The tooth is not so long as the
largest tooth of _P. molossus_, but is of proportionately greater
diameter and not so straight. It is conical and recurved, and shows
two very obscure cutting-edges, which divide the crown into two
unequal faces. It has faint longitudinal striations on all sides, and
the apex is sharp.
_Measurements._
M.
Fore-and-aft diameter at the base 0·613
Height of crown 0·020