Io6 UNIVERSITY OF COLORADO STUDIES 



lakes it is usually quite abundant to a depth of twenty feet. The stomach con- 

 tents of this species as examined by various writers in difTerent parts of the coun- 

 try show the food of the adult perch to be made up of large insects and their 

 larvae, crayfish and the young of other fishes, other food being taken as oppor- 

 tunity offers.' The Yellow Perch lays its eggs in long strings on a sandy bottom 

 near shore. These egg strings are not infrequently found entangled in the vege- 

 tation near shore. The spawning takes place in the latter part of April and 

 during May. 



Colorado specimens. — Colorado Stale Historical and Natural History Museum: Sloans Lake 

 near Denver, August 4, igoo (125 mm.), W. C. Ferril; Berkley Lake near Denver, August 18, 1900 

 (180 mm.), W. C. Ferril; Barr Lake, Adams County, July 20, 1907 (s specimens, 100-155 mm.), 

 H. G. Smith; State Teachers' College Museum: Lakes near Greeley, A. E. Beardsley; Colorado 

 College Museum: Cache la Poudre River near Greeley, I. C. Hall. 



Subfamily Etheostominae 

 The Darters 

 The fishes of this group are found only in the cold clear brooks, small streams 

 and shallow portions of the inland lakes of North America, particularly of the 

 northern portion of the Mississippi drainage. The species, which number a 

 hundred or more, are aU of the same general shape and have the same type of 

 behavior. Morphologically they differ from the other perches in the small, 

 fusiform body, the large pectoral fins and the much-reduced air bladder. Derived 

 from the true perch stock, they now occupy a very definite position in the ecology 

 of the small streams and lakes, in that they have taken the otherwise little-used 

 food supply existing under stones and on the bottom. By means of their well- 

 developed pectoral fins darters are able to hold themselves on the bottom against 

 a very rapid current of water, the much-reduced or almost functionless air bladder 

 making such a position possible. In this way darters have reached the headwaters 

 of many streams. The feeding habits and general activities of these interesting 

 little fishes show them to be, as Forbes has written, not so much dwarfed as con- 

 centrated fishes. When undisturbed the darter remains quietly on the bottom 

 with the pectoral fins braced, head upstream and the body often partly curled 

 about a stone or some other object. Upon becoming alarmed or otherwise inter- 

 ested a sudden movement of the pectorals places the fish some inches upstream, 

 where it immediately adjusts itself to the new surroundings^ appearing as a perma- 

 nent part of the whole. When taking food the darter approaches the prospective 

 prey carefully and cautiously, darting upon it suddenly and as quickly resuming 

 the absolute quiet which contrasts so strongly with its movements. The species 

 of darters, the breeding activities of which have been studied, mate in the spring. 

 At this time the males of some species have very elaborate nuptial colors. Few 



' See Hankinson, Rept. Mich. Geol. Biol. Survey for 1907, p. 215; Forbes Am) Richardson, Fishes of 

 Illinois, p. 277, 1909. 



