54 UNIVERSITY OF COLORADO STUDIES 



base of the first ray of the dorsal slightly behind the level of the ventrals; pec- 

 torals short, I or a little more in the head, not reaching the ventrals; ventrals 

 reaching the anal opening or the base of the anal fin; anal fin short, of 8 or 9 rays, 

 length of its base less than that of its longest ray; caudal peduncle rather narrow, 

 its least depth 2 or a little more in the head ; caudal fin rather broad and deeply 

 forked; scales large, closely imbricate, those on the sides broader than long, 6, 

 35-40, 3 ; lateral line complete, strongly decurved in the pectoral region; size small, 

 length under 4 inches, average adults 2.5 to 3 inches. 



Young and females pale olivaceous dorsally, with a bluish or lead-gray cast, 

 shading through dull silvery to almost white below; adult males dusky dorsally, 

 the region above the lateral line a bright steel blue, with a purplish or pinkish 

 iridescence; dull silvery below the lateral line; top of the head bluish; scales 

 in both sexes, especially above the lateral line, rather regularly outlined with 

 dusky or bluish, giving the sides a somewhat reticulated pattern; adults with a 

 long narrow triangular dusky violet humeral spot, margined behind with paler; 

 fins in all excepting breeding males rather hyaline, the dorsal and caudal some- 

 what dusky, and the anal and ventrals whitish; in breeding males, dorsal reddish, 

 pectorals, ventrals and anal yellowish to cherry-red ; the head and predorsal region 

 with small tubercles; operculum and sides of the body posterior to the violet 

 humeral spot with more or less red. 



The Redfin is one of the more abundant fishes of the western portion of the 

 Mississippi Valley, ranging from the Rio Grande River north through western 

 United States east of the Rocky Mountains into South Dakota, and east into 

 Illinois. 



Colorado specimens. — University Museum: St. Vrain Creek, Longmont, October 17, 1903 

 (6 specimens, 50-70 mm.), C. Juday and D. W. Spangler, No. 12; Lodgepole Creek near Ovid, 

 July 20, 1912 (32 specimens, 40-75 mm.), J. Henderson and M. M. Ellis, No. 364; Republican 

 River, Wray, October 26, 1912 (13 specimens, 30-85 mm.), A. G. Vestal and M. M. Ellis, No. 365; 

 4 miles west of Cripple Creek, July, 1913 (2 specimens, 165-170 mm.), F. A. Hassenpflug, No. 366; 

 Colorado State Historical and Natural History Museum: South Platte River near Denver, August 

 3, 1900 (65 mm.), W. C. Ferril; State Teachers' College Museum: Cache la Poudre near Greeley, 

 A. E. Beardsley. 



Genus PTYCHOCHEILUS Agassiz 

 The Squawfish and "White Salmon" 



Ptychocheilus Agassiz, Amer. Journ. Sci. Arts, p. 229, 1855. 



Very large carnivorous Cyprinids, the largest known North American Cypri- 

 nid being a member of this genus; body rather elongate; head long and pike- 

 like; alimentary canal short; caudal peduncle not abruptly narrowed just in 

 front of the caudal fin; basal fulcra of the caudal fin not strongly developed. 

 All of the species of this genus are found west of the Continental Divide. Ptycho- 

 cheilus is represented in Colorado by the "White Salmon." 



