FISHES OF COLORADO II5 



small, the spine bearing a thick pad on its ventral surface; anal long, length of its 

 base exceeding that of the spinous dorsal, of 11 or 13 rays the tips of which exceed 

 the webbing of the fin; caudal peduncle slender, its least depth varying from the 

 diameter of the eye to the length of the snout (the length of the snout equals the 

 diameter of the eye in yoimg specimens) ; caudal fin broad and fan-shaped, outer 

 margin rounded and not forked; scales wanting, lateral line prominent; skin 

 tough and leathery, varying from quite smooth to rather rough, as the prickles 

 are developed or not. 



General color bluish or brownish gray, mottled with irregular blotches of dark 

 brown or black; ventral parts while with a bluish or yeDowish cast, under parts 

 of the head, the sides, the pectoral fins and the ventral surface posterior to the anal 

 opening dusky with numerous minute black dots; fins dusky, rays and spines dark, 

 crossed by several series of white bars. Small specimens much lighter than adults, 

 rather uniformly covered dorsally with minute black dots. 



Because of the variation in the markings, the depth of the caudal peduncle 

 and the development of the prickles in the skin, several nominal species of sculpins 

 have been described from the Rocky Mountain region. These characters inter- 

 grade and extreme types may often be taken in the same collection. Considering 

 the extremes to represent subspecific types, three may be recognized, although 

 intergradations are found. 



a. Skin smooth. 



b. Caudal peduncle slender, its depth slightly exceeding the diameter of the eye. 



Cotlus punclulatus punctulatus 

 bb. Caudal peduncle deeper, its depth almost equalling that of the snout. 



Cotlus punctulatus vheeleri 

 aa. Skin with prickles, especially in the axils of the pectorals. . Cotlus punctulatus semiscaber 



The Rocky Mountain Bullhead or "Blob" as it is locally known reaches the 

 length of six inches, although average specimens are usually about three and one- 

 half inches long. In Colorado it is very abundant in the headwaters of the 

 Colorado River drainage, particularly in the Rio Florida and the Rio Las Animas 

 near Durango. It is foimd, however, on both sides of the range in the small 

 mountain streams. As its name implies, it is a species of the Rocky Mountain 

 region ranging from northern Montana south into New Mexico on both sides of 

 the Continental Divide, and west into the Great Basin in Idaho and Utah. 



This species is of considerable economic importance because of its feeding 

 habits. It moves about from stone to stone on the bottom of the stream, feeding 

 upon the small fish which take refuge under the stones, caddis-fly larvae and 

 snails. During the spawning season of the trout the Bullhead also consumes 

 quantities of trout eggs. This destruction of young trout and trout eggs is a 

 positive loss to the trout, for the young Bullheads are rarely if at all eaten by the 

 trout, there being no compensating relation between these two fishes like that 



