68 UNIVERSITY OF COLORADO STUDIES 



July 28, IQ12 (13 specimens, 65-95 mm.), M. M. Ellis, No. 383; four miles west of Cripple Creek, 

 July, 1Q13 (2 specimens, 100 and lis mm.), F. A. Hassenpflug, No. 384; Grape Creek, near Canyon 

 City, November 8, 1913 (s specimens, 70-90 mm.), A. G. Vestal and M. M. Ellis, No. 386; Sells 

 Lake, Canyon City, September, 1913 (90 mm.), F. A. Reidel, No. 385; Slate Teachers' College 

 Museum: Cache la Poudre, Greeley, and twenty miles above Antonito, A. E. Beardsley; Colorado 

 State Historical and Natural History Museum: South Platte River near Denver, August 3, 1900 

 (2 specimens, 65-75 mm.), W. C. Ferril. 



Genus AGOSIA Girard 

 The Western Dace 

 Agosia Girard, Proc. Acad. Nat. Sci. Pkila., p. 186, 1856. 



General characters the same as Rliinichthys from which this genus differs in 

 the protractile premaxillaries. Premaxillaries protractile, upper lip not continu- 

 ous with the skin of the top of the head, no frenum. Species of the Rocky Moun- 

 tain region on the west slope, ranging northward through the Great Basin into 

 the Pacific region and south through the Colorado River drainage. Size small, 

 length 5 inches or less. 



Agosia yarrowl Jordan and Evermann 

 Yarrow's Dace (Figs. 32 and 33) 



Agosia yarrowi Jordan and Evermann, Bull. U.S. Fish Com., Vol. IX, p. 28, 1889 (Tomichi 

 Creek and Gunnison River, Gunnison; Uncompahgre, Delta; Eagle River, Gypsum; Rio d. 1. 

 Animas; Rio Florida; Lightner's Creek). 



Apocope oscula (Girard) — Cope and Yarrow, Wheeler Survey, Vol. V, p. 647, 1875 (Pagosa), 

 wrongly identified. 



Body elongate, subterete, slightly compressed; depth 4. 25 to 5. 5 in the length 

 to the base of the caudal; head slightly depressed, long and pointed, its length 

 3.5 to 4.5 in the length; dorsal profile of the head sloping anteriorly, ventral 

 profile rather straight; snout produced, overhanging the mouth; eye prominent, 

 situated near or slightly above the center of the head, its diameter 2 to almost 

 3 in the snout, i . 5 to 2 in the interorbital distance, 4. s to 6. 5 in head; nostril large 

 and prominent, just in front of and somewhat dorsal to the eye; mouth ventral, 

 sucker-like, lips large and fleshy, the upper recurved around the angle of the mouth; 

 a small but distinct barbel in the depression at the junction of the upper and lower 

 jaws; premaxillaries protractile, no frenum connecting the upper lip with the skin 

 of the top of the head (a narrow frenum sometimes present) ; dorsal fin rather 

 short, length of its base less than the length of its longest ray, base of the first ray 

 of the dorsal nearer to the base of the caudal than to the tip of the snout, inserted 

 just above or slightly behind the level of the origin of the ventrals, dorsal rays 7-9; 

 pectorals medium to small, not quite or just reaching the ventrals; ventrals 

 smaller than the pectorals, reaching the anal; anal fin of much the same size and 

 shape as the dorsal, of 7 or 8 rays; scales usually about 14 to 16, 77-89, 13 to 15; 

 lateral line complete or interrupted, little if at all decurved; size rather small, 

 length 5 inches or less. 



