99 



CA TOSTOMIDyE. 



Body covered with scales ; head naked ; margin of upper 

 jaw formed by the premaxillaries; mouth toothless. Pharyn- 

 geal 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 Bubalichtliys. Dorsal fin elongate, with a few 

 fulcral spines in front. There are three broad branchioste- 

 gals. The vertebrae are short, and the hEcmal spines of the 

 caudal fin are distinct and rather narrow. The teeth are ar- 

 ranged 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 Castel- 

 lo's Ranch, Col. 



SA URODONTID^E. 



For a very complete definition of this family, see Cope's 

 Cretac, Vert., p. 183. 



PORTHEUS, Cope. 



Cretac. Vert., p. 189 et seq. 



" Teeth subcyHndric, 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 



