The Food of Yoioig Fishes. 75 



cavity. This intestine ^vas well tilled with nuid with only 

 a slight sprinkling of unicellular Alga^. 



Much as these young resemble young Cyprinida% they 

 can be easily distinguished from them by the very long 

 anal hn ; and from the brook silversides (Labidesthes), to 

 which they bear some superficial resemblance, by the ab- 

 sence of a spinous dorsal. 



These twelve fishes, all under two inches in length, had 

 eaten about ninety per cent, of Entomostraca, two per 

 cent, of Chironomus larvtV, and for the remainder, Algae. 

 The Crustacea were about equally Cladocera and Copepoda. 

 Among the former were Daphnla pulex., Simocephalus 

 americanus, Cerioclaphnia dentata., Bosmina, Chydorus and 

 Alona. In a specimen three-quarters of an inch long which 

 I took from the stomach of a Morone intemfpfa, I found a 

 few specimens of Leptodora hi/aJina (?) Lillj. The Copep- 

 oda were all Cyclops, so far as recognizable.' 



Cyprinid^. 



A single minute minnow, three-eighths of an inch long, 

 which 1 could not determine specifically, had eaten Daph- 

 nids (twenty-five per cent.) and Chironomus larvjt. 



The specimens of the common ehuh mimioio {Semotilics 

 corporal is), ranging from five-eighths inch to one inch, 

 indicate somewhat doubtfully an exception to the general 

 rule respecting the early food of fishes. Only seven per cent, 

 of their food was Entomostraca, and the whole remainder 

 consisted of filamentous Alg.v. It should be noted, how- 

 ever, that twenty per cent, of the food of the smallest 

 specimen, which was five-eighths of an inch long, was Cy- 

 clops, and it may be that Semotilus lives wholly on Ento- 

 mostraca at first, merely changing its habit earlier than 

 most of its allies. 



Two specimens of JVotropis, an inch and a half in length, 

 had eaten nothing but Daphnids. 



Catostomid^. 



Thirty specimens, representing five genera of this pe- 

 culiar family, were studied. A very curious feature of 

 the food of the young is the frequent dependence of suck- 



