62 FISHES OF ILLINOIS 



The family is found in the fresh waters of North America at 

 large, in which about 15 genera and 60 species occur; and there 

 are 2 species also in eastern Asia. They range in length from 6 

 inches to 3 feet. The suckers have usually been regarded by 

 European writers as a subfamily of Cyprinidce, from which they 

 differ chiefly in the structure of the mouth and the lower pharyn- 

 geal bones. They are generally of sluggish habit and, as a rule, 

 prefer water of good depth and little current, but some of them 

 may be found in almost every stream and pond within their 

 range. Their spring migration is familiar to all fishermen, and 

 to many who do not fish, all of our species running up the 

 smaller streams in May or June to deposit their eggs. The males 

 of most species develop black or red pigment on the body and 

 fins in spring, and in many kinds peculiar wart-like tubercles, 

 called pearl organs, appear at this season on the head, fins, and 

 caudal peduncle. 



The suckers are, on the whole, an unusually homogeneous 

 group as represented in Illinois, not only agreeing in the character 

 of their feeding structures which gives them their common 

 name, but unusually similar also in their movements, habits, 

 modes of life, and places of most frequent resort. They feed, 

 without exception, on the bottom of the waters they inhabit, 

 and commonly on substantially the same kinds of food, differing 

 somewhat in respect to the places in which they seek it. The 

 buffalo-fishes, for example, are from 2^ to 3 times as abundant 

 in our collections from the bottom-land lakes as they would be 

 if they had been equally distributed throughout all waters. In 

 other words, the frequency coefficient of one of the two buffaloes 

 is 2.26 for lowland lakes and that of the other is 2.93. On the 

 other hand, the common sucker, the chub-sucker, and the striped 

 sucker show a decided preference for the smaller streams, their 

 coefficients of frequency in creeks being 4.27, 3.41, and 3.17 for 

 the three species respectively. The most marked departure 

 from the average habit of the family is made by the hogsucker, 

 or stone-roller (Catostomus nigricans), which especially frequents 

 swift water on rocky stretches of the larger streams, filling there 

 the place which the darters occupy in creeks and brooks. 



Notwithstanding these divergencies in local distribution, the 

 family as a whole forms'a rather definite ecological group, as is 

 shown especially by the frequency with which representatives of 

 the several species are found in company in the same situations 

 and appear together, consequently, in our collections. The 



