FISHES OF COLORADO 59 



spring, the eggs being deposited in a shallow excavation made in the sand or 

 gravel by the male. 



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

 (2 specimens, 90 and 180 mm.), C. Juday and D. W. Spangler, No. 7; Boulder Creek, Boulder, 

 October, 1903 (59 specimens, 35-190 mm.), C. Juday and J. Henderson, No. 8; Boulder Creels 

 east of Boulder, May, 1909 (3 specimens, 95-120 mm.), David Rusk and Donald Kloke, No. 30; 

 Sterling, June 10, igio (115 mm.), H. G. Smith, No. 370; West Plum Creek near Castle Rock, 

 June 8, 1912 (90 specimens, 50-135 mm.), A. G. Vestal and M. M. Ellis, No. 371; South Platte, 

 Julesburg, July 19, 1912 (395 specimens, 30-140 mm.), J. Henderson and M. M. Ellis, No. 372; 

 Lodgepole Creek near Ovid, July 20, 1912 (37 specimens, 35-140 mm.), J. Henderson and M. M. 

 Ellis, No. 373; Boulder Creek 6 miles east of Boulder. July 25, 1912 (84 specimens, 30-110 mm.), 

 M. M. Ellis, No. 374; Republican River, Wray, October 25, 1912 (125 specimens, 45-190 mm.), 

 A. G. Vestal and M. M. Ellis, No. 375; Slate Teachers' College Museum: Cache la Poudre near 

 Greeley, A. E. Beardsley. 



Genus COUESIUS Jordan 

 The Mountain Dace 



Couesius Jordan, Bull. Bayden Geol. Survey Terr., Vol. IV, p. 785, 1878. 



General characters the same as Semotilus to which this genus is very closely 

 related and from which it differs in the number of pharyngeal teeth. These are 

 2-4-4-2 in Couesius and 2-5-4-2 in Semotilus. The species of the genus Couesius 

 have not been studied in detail so that at present this genus is rather uncertain. 



A single species, Couesius dissimilis, is known from Colorado. 



Couesius dissimilis (Girard) 

 Mountain Dace 



Leucosomus dissimilis Girard, Proc. Acad. Nat. Sci. Phila., p. 189, 1856 (Milk River and 

 Little Muddy River, Montana). 



Couesius dissimilis (Girard) — Juday, Univ. Colo. Studies, Vol. II, p. 113, 1903 (Boulder); 

 Juday, Bull. U.S. Fish Com. for IQ04, p. 227, 1905 (Boulder). 



Body elongate, somewhat fusiform; head conical, moderately short, its 

 length a little more or a little less than the greatest depth of the body; in adult 

 specimens depth 4 to 4.75, head 4.25 to 4.5 rarely 4, in the length to the base 

 of the caudal; eye rather large, 4 to 5 in the head, about i . 5 in the snout, 2 or a 

 little less in the interorbital distance; mouth large, terminal and oblique, angle 

 of the mouth not reaching the level of the anterior margin of the eye, barbel 

 prominent, attached on the upper, outer surface of the upper jaw, just above the 

 junction of the upper and lower jaws, but its free portion dropping downward 

 and back into the groove at the junction of the two jaws; dorsal fin short and 

 rather high, of 8 rays, length of its base less than the length of its longest ray; 

 pectorals short, about i . 25 to i . 5 in the head, not reaching the ventrals by almost 

 the length of the latter; ventrals barely reaching the anal opening; anal fin short, 

 of 8 rays; least depth of the caudal peduncle about 2 or 2.5 in the head; caudal 



