182 FISHES OF ILLINOIS 



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 catfishes. 



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 speci- 

 mens, however, had eaten nothing but algae, 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, commonly, 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 15 of the 43 fishes. They 

 amounted to 15 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 s&y 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 having 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 Vivipara) 

 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 larvae of day-flies, dragon-flies, and gnats, 



