206 CONTRIBUTIONS TO NOETH AMERICAN ICHTHYOLOGY IV. 



Hayden'a Geol. Surv. Wyom. 1870, 440, 187iJ; Jordan, Bull. Hayden's Geol. Surv. Terr. 

 iv, No. 3, 66B (a rather chubby specimen from the Rio Grande, with scales 6-45-7, 

 the breast ualicd, is referred by us to thia species) : ? Phenacohiits teretuhis var. liosternua 

 Nelson, Bull. Ills. Mus. Nat. Hist, i, 1876, 4G.) 



** Scales small, about 60 in the lateral hue, 



3il. P. catostonaus Jordan. 



Body rather slendei", nearly terete, scarcely compressed at all, back 

 not elevated, caudal peduncle stout. Head very large, the muzzle blunt 

 and heavy, the cheeks tumid. Mouth small, inferior, altogether below 

 the level of the eye, the maxillary barely reaching to the nostrils. Eyes 

 large, high up, behind middle of head, and 3J in its length. Scales 

 small, thin, and loosely imbricated ; the back and belly scaled ; chest 

 naked. Lateral line nearly straight. Twenty-two scales in front of 

 dorsal. Fins all small. Width of isthmus 2^ in head. Pale oliva- 

 ceoijpj white below; a silvery lateral band, underlaid by dusky, which 

 forms a vague blotch at base of caudal; back dusted with dark specks; 

 top of head black; a yellowish vertebral line. Head 4^; depth 5f. D. 

 8; A. 7; scales 7-G0-5; teeth 4-4. L. 4 inches. Alabama Eiver. 



(Jordan, Ann. Lye. Nat. Hist. N. Y. 1876, 3:52. ) 



312. P. iiranoips Coijc. 



Body very slender, little compressed, back not elevated, caudal pe- 

 duncle long and slender. Head long and rather slender, flat above, 

 the muzzle broad, blunt, and projecting. Mouth entirely inferior, larger 

 than in the other species, with consjjicuous lips. Eye large, placed very 

 high, behind the middle of the head, 3-^ in head. Scales small, 24 iu 

 front of dorsal. Lateral line straight. Chest and middle line of belly 

 naked. Width of isthmus half length of head. Fins small. Head 4f ; 

 depth 6. D. 8; A. 7; scales 7-60-6; teeth 4-4. Tennessee Eiver. 



(Cope, Proc. Acad. N.at. Sei. Phila. 1867, 96.) 



* 



89.— RHIWICHTHYS Agassiz. 



Black-nosed Dace. 



(Argyreus Heckcl, iireoccuiiied in Entomology.) 

 (Agassiz, Lake Superior, 1850, 353: type Cyprinua atronasus MitchiU.) 



Body rather elongate, not much compressed. Mouth small, subia- 

 ferior, normal, the upj^er jaw a^ot protractile, the upper lip continuous 

 with the skin of the forehead, a barbel terminal on the maxillary. 

 Teeth mostly 2, 4-4, 2, hooked, without grinding surface. Intestinal 



