PLECTOSPOND YLI CYFRINIDAE M. PAEO VAM US. 



669 



MYLOLEUCUS, Cope. 



A new genus, established by Professor Cope in 1871 upon specimens 

 received from Warm Springs, Utah. 



" Teeth raptorial, but with well-developed masticatory surface ; 54 in 

 outer row. No barbels ; lateral line well-developed. Dorsal fin above or 

 in front of line of ventrals. This genus is Siboma, with developed grinding 

 surfaces of the teeth." 



MYLOLEUCUS PULVERULENTUS, Cope. 



Mylolcucus pulverulentus, COPE, U. S. Geol. Surv. Montana & Adjacent Territories, 

 1871, 475. 



Seen by members of the survey, but no specimens received in Wash- 

 ington. 



MYLOLEUCUS PAROVANUS, Cope. 



Myloleucus parovanus, COPE, Proc. Am. Phil. Soc. Phila., 1874, 136. Id., Rep. Plagop. 

 & Ichth.v. Utah, 1874, 10. 



PLATE XXVIII, FIGS. 3, 3a. 



With a general similarity to Gila montana, this fish may be readily 

 determined by the generic characters of the teeth and fins, as well as 

 by the reduced number of radii of the anal fin. The genus Myloleucus 

 was established, as already noted, in 1871, for species resembling' Siboma, 

 in having the pharyngeal teeth of the longer row 4-5, and the origin of 

 the dorsal fin situated in advance of the ventral, but differing in the posses- 

 sion of well defined masticatory surfaces on the teeth. The typical species 

 of M. pulverulentus, Cope, is from the Warm Springs of Utah ; a fish which 

 differs from the present one in the greater stoutness of form and smaller 

 and more numerous scales. 



