42 UNIVERSITY OF COLORADO STUDIES 



arranged in three rows between the nostrils and the margin of the upper lip, and in 

 two rows below the lower lip; three or more smaller tubercles just in front of the 

 eye; males at other than the breeding season much like adult females, but more 

 brassy in color and with a more or less dusky head. 



This species spawns in late spring, laying its eggs in sheltered places under 

 stones and debris in shallow excavations. Males in breeding colors and with 

 tubercles, and females with the abdomen much distended with eggs were taken 

 from West Plum Creek at an altitude of 6,500 feet June 8, 191 2, and from Glacier 

 Lake, Boulder County, at an altitude of 9,500 feet on July 30, 191 2. The smallest 

 breeding male found was 55 mm. in length and the smallest female distended with 

 eggs was 30 mm. long. Many of the Plum Creek specimens were badly infected 

 with larval trematodes. Like the other small herbivorous Cyprinids with long 

 intestines, the Black-headed Minnow feeds upon slime and ooze and the contained 

 substances. The alimentary canals of the many specimens opened were packed 

 with dark masses of this material. 



The Pimephales maculosus Girard described from the Arkansas River and 

 based on specimens with a rather complete lateral line is here considered synony- 

 mous with P. promelas since individuals in a single collection from the Republican 

 River at Wray were found with quite complete and very incomplete lateral lines. 



Pimephales promelas ranges throughout the western and upper portions of the 

 Mississippi Valley and Great Lakes region. It is a species of the quieter, more 

 weedy parts of small streams. 



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

 (70 mm.), C. Juday and D. W. Spangler, No. 26; West Plum Creek near Castle Rock, June 8, 

 1912 (is specimens, 45-80 mm.), A. G. Vestal and M. M. Ellis, No. 336; Lodgepole Creek near 

 Ovid, July 20, 1912 (75 mm.), J. Henderson and M. M. Ellis, No. 337; Glacier Lake, Boulder 

 County, July 30, 191 2 (240 specimens, 45-55 mm.), Howell Ellis, No. 338; Boulder Creek 6 miles 

 east of Boulder, July 25, 1912 (60 mm.), M. M. Ellis, No. 339; Republican River, Wray, October 

 26, 1912 (504 specimens, 30-80 mm.), A. G. Vestal and M. M. Ellis, No. 340; Sells Lake, Canyon 

 City, September, 1912 (2 specimens, 40-45 mm.), F. A. Reidel, No. 341; State Teachers' College 

 Museum: Cache la Poudre near Greeley, A. E. Beardsley. 



Genus HYBOGNATHUS Agassiz 

 The Silvery Minnows 

 Hybognathus Agassiz, Amer. Journ. Sci. Arts, p. 223, 1855. 



Small herbivorous Cyprinids; alimentary canal 3 to 8 times the length of the 

 body; peritoneum black; inner surface of the lower jaw with a small, hard pro- 

 tuberance near the tip; premaxillaries usually protractile; no maxillary barbel; 

 first (rudimentary) ray of the dorsal fin adnate to the second; base of the first 

 dorsal ray in front of the level of the ventrals. Species of central and southern 

 United States and northern Mexico. 



