The Food of Fresh-Wattr Fishes. 457 



Forty-three specimens of this species were taken from the 

 Illinois River at Peoria, Pekiu, and Havana, and from the Mis- 

 sissippi River, near Quincy. Their dates of capture represent 

 the spring, summer, and autumn months of the years 1878, 1880, 

 and 1887. 



About a fourth of the food consisted of vegetable matter, 

 much of it miscellaneous and accidental, but chiefly Algae — 

 Cladophora being the most abundant form. This and other 

 filamentous Algae made a large part of the food of several 

 fishes taken in October, 1878 and 1887, three having eaten 

 nothing else. Fragments of Potamogeton were taken by other 

 October specimens, making twenty per cent, of the food of 

 three. The fact that the floating Lenina occurred but rarely, 

 and then in the smallest quantity, is evidence that these cat- 

 fishes are strictly bottom feeders. A single specimen had 

 fed on still-house slops, as shown by the considerable amount 

 of meal in its alimentary contents. 



A dead rat, pieces of ham, and other animal debris attest 

 the easy-going appetite of this thrifty species. 



Fragments of fishes were found in eleven examples of this 

 group, — commonly, however, in pieces so large as to make it 

 certain that they were derived from those already dead. Occa- 

 sionally, as in examples taken in August, 1887, from the Mis- 

 sissippi River, fishes probably taken alive composed the whole 

 of the food. The species were not identifiable. 



Molluscan food was a decidedly important element, being 

 found in fifteen of the fishes and amounting to fifteen per cent, 

 of the whole. Several specimens had taken little or nothing else, 

 — notably six secured at Havana in September, 1887, and one 

 at Peoria in October of the same year. The Mollusca were 

 about equally divided between gasteropods and lamelli- 

 branchs, the former largely Melantho and Vivipara, the latter 

 usually Unio or Anodonta. 



Notwithstanding the number of bivalves eaten by these 

 fishes, no fragment of a shell was ever found in their stomachs, 

 but the bodies of the animals had invariably been torn from the 

 shell while yet living — as shown both by the fresh condition 

 of the recently ingested specimens and likewise by the fact that 

 the adductor muscles were scarcely ever present in the frag- 



