56 



Probably to those accustomed to the abundance of true 

 luonns in marine situations, no feature of the poverty of fresh- 

 water Hfe will be more striking than the small number of this 

 subkingdom 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 appreciably 

 affecting any of the important ratios. Catfishes alone seem 

 purposely to eat leeches, these occurring in nine specimens of 

 three different species of this family, and also in one common 

 sucker and in a single shovel-fish. One of the fresh-water 

 Sponges (Spongilla) had been eaten in considerable quantities 

 by two examples of the spotted cat taken in September, but 

 this element was not encountered elsewhere in my studies. 



That the minutest and simplest of all the animal forms, far 

 too small for the eye of a fish to see without a microscope, 

 should have been recognized in the food of seventeen species of 

 fishes is, of course, to be explained only as an incident of the 

 feeding habit. It is possible, however, that these Protozoa, 

 where especially abundant, may be recognized in the mass by 

 the delicate sensory structures of the fish ; and they seem in 

 most cases to have been taken with mud and slime, rich in 

 organic substances. As most of them are extremely perishable, 

 and can scarcely leave a trace a few seconds after immersion in 

 the gastric juices of the fish, it is probable that they contribute 

 much more generally than our observations indicate to the food 

 of some fishes, especially to those which feed upon the bottom. 



Young suckers under six inches in length clearly take them 

 purposely, substituting them in great part for the Entomostraca 

 taken by other fishes of their size and age. 



I detected Protozoa in the food of several genera of Cyprin- 

 idae, in the young of buffalo, the river carp, the chub sucker, 

 the red-horse, the stone roller, in the common sucker, in a sin- 

 gle gizzard shad, in a stone-cat, and in a top minnow. 



The only scavenger ^'i\i&'=> of our collection were three species 

 of the common catfishes ; the spotted cat, the yellow cat, and the 

 marbled cat — all of which had eaten dead animal matter, includ- 

 ing pieces of fish, ham, mice, kittens, and the like. A single 



