FISHES OF COLORADO 4 1 



short and broad, its top usually somewhat flattened; no maxillary barbel; first 

 (rudimentary) ray of the dorsal fin separated from the second, short, thick and 

 blunt, especially so in the males; lateral line more or less incomplete. Species 

 of the Mississippi Valley, represented in Colorado by the Black-headed Minnow. 



Pimephales promelas Rafinesque 

 Black-headed Minnow, Fat-head (Figs. 15, 17, 18 and 19) 



Pimephales promelas Rafinesque, Ichthyologia Ohiensis, p. 53, 1820 (pond near Lexington, 

 Kentucky); Judav, Univ. Colo. Studies, Vol. II, p. 113, 1903 (Longmont); Jubay, Bull. U.S. 

 Fish Com. for IQ04, p. 226, 1Q05 (Longmont). 



Pimephales promelas co«/er/«j(Girard) — JORDAN, Bull. U.S. Fish Com., Vol. IX, p. 16, 1889 

 (Arkansas at Canyon City; Pueblo; pond near Canyon City; Fountain Creek near Pueblo). 



Pimephales maculosus Girard, Proc. Acad. Nat. Sci. Phila., p. 180, 1856 (sluices of the Arkan- 

 sas River, Ft. Makee. Arkansas). 



Hyborhynchus nigellus Cope, Wheeler Survey, Vol. V, p. 671, 187s (Arkansas River, Pueblo). 



Body short, deep and stout, slightly compressed; head short and rather 

 globose, its length about equal to the depth of the body; depth 3. 25 to 4 in the 

 length to the base of the caudal; eye 4 to 4. s in the head, equal to or a little less 

 than the snout, 2 to 3 in the interorbital distance; mouth terminal and small; 

 angle of the mouth not reaching the level of the anterior margin of the eye by 

 about the diameter of the eye; nostril large, prominent, septum high; dorsal 

 fin short, length of its base equal to or less than the length of the longest ray; first 

 ray of the dorsal, especially in breeding males, short, thick and blunt, separated from 

 the second ; base of the first dorsal ray on a level with or slightly in front of the 

 ventrals; dorsal rays, not counting the first short thick one, 7 or 8; pectorals 

 short, not reaching the ventrals by the diameter of the eye; ventrals reaching to 

 the anal opening or beyond ; anal fin short ; anal rays, not counting the first short 

 thick one, 7; caudal peduncle broad, its least depth less than 2 in the head; 

 caudal fin deeply forked; scales 8 or 9, 45-55, 5 or 6; lateral line more or less 

 incomplete, rather straight; length 4 inches or less, average specimens about 3 

 inches in length. 



Color of young and females olivaceous above, shading to yellowish below, with 

 a rather distinct mid-dorsal dusky stripe; yoimg with a dusky lateral stripe 2 to 

 4 rows of scales wide, extending from behind the gill opening to the base of the 

 caudal fin; this stripe usually wanting or incompletely developed in adult males 

 and often very much reduced in adult females; sides of the body with a brassy 

 luster; scales more or less outlined with dusky; fin rays often dusky. Breeding 

 males with the entire head excepting the posterior margin of the operculum dusky 

 to jet black; outer third of the dorsal fin dusky, its first 2 or 3 rays, including the 

 first blunt ray and the basal two-thirds of each of the remaining rays, dusky to 

 jet black; membranous portion of the fins hyaline; the pre-dorsal region more or 

 less swollen; anterior portion of the head with conical, white or yellow tubercles 



