158 CONTKIBUTIOXS TO NORTH AMERICAN ICHTHYOLOGY IV. 
COLISCUS Cope. 
(Coiie, Hayden’s Geol. Surv. Wyom. 1872, 4:17 : type Coliscus parietalis Cope.) 
This genus differs chiefly from Hybognathus in hat ing the lateral line 
incomplete or obsolete. The mouth is oblique, and the dorsal fin in 
advance of the ventrals. (xo/lo?, deficiency 5 in allusion to the incomplete 
lateral line.) 
190. C. pas'BCtaSis Cope. 
Body moderately elongate. Head wide, especially behind. Muzzle 
obtuse. Lips equal. Mouth descending obliquely, the maxillary not 
quite reaching the orbit. Eye 3§ in head. Scales small, the tubes of 
the lateral line present on 7 of them ; 14 in a transverse series. Dorsal 
fin midway between snout and caudal. Suborbital bones slender. Col- 
oration silvery, unspotted. D. 7; A. 85 Lat. 1. 42; teeth 4-4. L. 2-3 
inches. Missouri Eiver at Saint Joseph. {Cope.) 
(Cope, Geol. Surv". Terr. Wyom. for 1870, 1872,437; Jordan, 289.) 
79 , — PIinEPSIALES Rafinesqne. 
Fat-heads. 
(Rafinesqne, Ichth. Oh. 1820,52: tjpo Pimephales promelas 'RaL) 
Body short and stout, little compressed. Head short and rounded. 
Mouth small, inferior ; iqiper jaw protractile; no barbel. Teeth 4-4, with 
oblique grinding surface, usually but one of the teeth hooked. Dorsal 
over ventrals, its first (rudimentary) ray separated from the rest by 
membrane. Anal basis short. Intestinal canal elongate. Peritoneum 
black. Pseudobrauchim present. Scales rather small. Lateral line 
iucomidete. Size small, (rrf/jts;.?;?, fat; xs<paX-^., head.) 
191. P. pt'OGiieSas Raf. — Fat-head; BJaclc-head Minnow. 
Body very short and deep. Head short, everywhere convex, almost 
globular in adult males. Mouth small, inferior, horizontal. Scales 
deep, closely imbricated. Lateral line almost wanting, on 5-20 scales 
only. Olivaceous, the dorsal with a large black bar across it, nearly 
half way up, most distinct anteriorly, appearing as a simple dusky 
shade in the young. Male fish dusky, the head jet-black, with several 
large tubercles on the snout in spring. A dusky shade along sides of 
caudal peduncle. Head 4; dei)th 4. D. I, 7; A. 7; scales 7-47-6; teeth 
4-4. L. 2 ^ inches. Ohio Valley to the Upper Missouri; generally 
abundant in sluggish brooks. Varies greatly with age, sex, and season. 
(Raf. Ichth. Oh. 53: Flmcphales fasciatus Grd. Proc. Acad. Nat. Sci. Phila. 1856, 
180 : Plargyrus melanocephalus Abbott, Proc. Acad. Nat. Sci. Phila. 1860, 325: Pimephales 
