182 FISHES OF ILLINOIS 



swiftly flowing water," for these reasons being well esteemed by 

 anglers in many localities. Its flesh is likewise firmer, and perhaps 

 more flaky and better flavored than that of any of the other cat- 

 fishes. 



Our knowledge of its food is based upon an examination of 43 

 specimens taken from the Illinois and the Mississippi rivers during 

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

 1887. About a fourth of the food consisted of vegetable matter, 

 much of it miscellaneous and accidental. Three specimens, how- 

 ever, had eaten nothing but algse, and fragments of pondweed 

 (Potamogeton) made 20 per cent, of the food of another three. A 

 single fish had fed on still-house slops ; and a dead rat, pieces of ham, 

 and other animal debris attested the easy-going appetite of this 

 thrifty species. Pieces of fish were found in all of this group, com- 

 monly, however, of so large a size as to make it certain that they were 

 the debris of the fishing boats. Occasionally fishes evidently taken 

 alive composed the whole food. Mollusks, about equally large water- 

 snails and large thin clams (probably in most cases Anodonta) , were 

 a decidedly important element, being found in 1 5 of the 43 fishes. 

 -They amounted to IS per cent, of the food of the group, and several 

 specimens had taken little or nothing else. Notwithstanding the 

 •number of bivalves eaten by this fish, no fragment of a shell was ever 

 found in their stomachs, but the bodies of the mollusks seem to 

 have been separated, while yet living, from the shells, as indicated 

 by their fresh condition and by the fact that the shell muscles 

 were scarcely ever present. Fishermen say that they are often 

 first notified of the presence of catfishes in their seines by seeing 

 the fragments of clams floating on the surface, disgorged by the 

 struggling captives. Still more interesting. and curious is the fact 

 that the spiral-shelled mollusks found in the : stomachs of these fishes 

 were almost invariably naked, the more or less mutilated bodies hav- 

 ing only the opercles attached. The shells are evidently cracked in 

 the jaws of the fish and rejected before the food is swallowed. As 

 many as 120 bodies and opercles of water-snails (Melantho and Vivip- 

 ara) were by us taken from the stomach of a single Illinois River cat- 

 fish. Insects were, however, a principal food of the specimens 

 studied, making 44 per cent, of all, and eaten by 28 of the fishes. 

 Five, in fact, had eaten nothing else, and others had taken 90 per 

 cent., or more, of insects, mostly aquatic, although now and then a 

 fish had filled itself with terrestrial specimens. Most of the aquatic 

 insects were larva; of day-flies, dragon-flies, and gnats, to be found 



