42 CLARENCE L. TURNER Vol. XXII, No. 2 



species and ranging in size from ten to one hundred millimeters. 

 Six hundred and twelve of these covering a wide range in 

 locality, kind of habitat, date of capture and age of individual 

 were examined. 



METHODS. 



All the measurements of length include the distance from 

 the base of the caudal fin to the tip of the jaw or snout. 



Very few specimens were examined in a fresh condition, 

 nearly all being preserved in strong formalin as soon as taken. 



Various kinds of seines were furnished by the Bureau of 

 Fish and Game and practically all the fish were taken by seining. 



In determining the quantity and character of the food the 

 stomach and intestine were dissected out with the aid of a 

 binocular microscope, the contents removed and, so far as 

 possible, identified. A compound microscope was also employed 

 for the identification of smaller objects, after which quantitative 

 estimates of the various articles of food were made. 



FOOD OF EACH SPECIES. 



There is a general similarity in the food of the different 

 species. The most typical feed almost exclusively in their 

 younger stages upon entomostraca and minute midge larvae, 

 later increasing the amount of midge larvae at the expense of 

 the entomostraca. It is worthy of note that larger specimens 

 of midge larvae are taken as the fishes increase in size. Still 

 later the young fishes turn to larger insect larvae and this is 

 their staple adult food. Forbes shows that the younger fishes 

 of most families pass through these stages and then become 

 more specialized as adults, eating fish, molluscs, vegetation 

 or even one-celled organisms. Several variations from the 

 generalized food habits occur among the darters and the details 

 of such variations will be taken up in the discussion of each 

 group. 



