06 



Notemigonus and Notropis among the minnows, represented in my col- 

 lections by one hundred and twenty-five and one hundred specimens re- 

 spectively, had obtaincfi about a sixth of their food from Entomostraca. 



Ten per cent, of the for)d of the sucl<er family consisted of them, mostly 

 taken by the deep-bodied s])ecies Carpiodes and Ictiobus. in which they 

 made a fourth or a fifth of the entire food. This fact is explained, it 

 will be remembered, Ity the rclativeh'' long, slender, and numerous gill- 

 rakers of these fishes. Large river-buffalo were occasionally crammed with 

 the smallest of these Entomostraca, — the minute Canthocamptus. only a 

 twenty-fifth of an inch in length. 



I have several times remarked the peculiar importance of Entomostracii 

 to the shovel fish, — one of the largest of our fresh-water animals, — a fact 

 accounted for l)y the remarkable branchial strainer of this species, proba- 

 bly the most efficient apparatus of its kind known to the ichthyologist. 

 Here, again, the smallest forms were the most abundant.- Generally, 

 however, the Cladocera were more common than the other orders, the 

 bivalve Cypris (most frequent in the mud) being much less abundant in 

 the food. I have shown elsewhere.* at length, that Entomostraca com- 

 pose by far the greater part of the food of young fishes of all descrip- 

 tions, — with the partial exception of the sucker family, the young of 

 which feed largely on still more minute organic forms. — and present an 

 abstract of these facts in this article under another head.t 



Particulars concerning ihe use of this abundant and varied group as 

 food for tlshes, are so numerous as to make them difficult to summarize, 

 and the Interested reader Is again referred to the detailed list accom- 

 panying this paper. 



VERMES AS FOOD FOK FISHES. 



Probably to those accustomed to the abundance of true worms (Vermes) 

 in marine situations, no feature of the poverty of fresh-water life will be 

 more striking than the small number of this sub-kingdom occurring in 

 the course of miscellaneous aquatic collections in the interior. Similarly 

 we notice that in the food of fishes the occurrence of Vermes is so rarely 

 noticed that they might be left out of account entirely without appre- 

 ciably affecting any of the important ratios. 



The minnows (cyprinoids) had eaten more of them than any other 

 family. — three per cent, of the food of twenty-two specimens of Scmotilus 

 being credited to them, and one per cent, of that of thirteen si>ecimens 

 of Pimephales. besides a trace in tlie food of Notropis. More precisely 

 analyzed, we find that a single Kais. a Lumbriculus, two examples of 

 (xordius (doubtless taken as insect parasites) and several minute rotifers 

 (wheel-animalcules) are the forms upon which this estimate is based. 



A trace of Vermes likewise^ apjiears in the food of suckers. — mostly a 

 poly/.oan species (Plumatellal and minute rotifers sucked up witli the 

 mud. 



Cattlshes alone seem purposely to eat leeches, these occurring in nine 

 specimens of three different si)ecies of this family, and also in one com- 

 mon sucker and in a single shovel tish. Tliis leech last menticmed and a 

 small quantity of Plumatella were tiie only Vermes eaten by tlie shovel 

 tlshes which i examined. 



A ])lanarian worm occurred in on(> small stone cat. while rotifers were 

 recognized in a common miimovv. eight young red-horse, six young chuVt 

 suckers', five of the common sucker'-', a single Corpiodes (.voung), and 

 seven young buffalo. Polyzoa were noted, in addition to the instances 

 al)ove ment ioned, in four common s\intishes. the croppie. and seven buffalo. 



* Bull. 111. St. Lab. Nat. Hist.. Vol. I.. No. S, pp. 75,70. 



+ See pp. 495 ami 496. 



1 Eriinyzon sucetta. 2 Catostomus tores. 



