Chapter 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._