[11] AN INDIRECT SOURCE OF THE FOOD OF FISUES. 765 



g(\stible. beiug thrown out of the vent, as in CJiirocpehala, in the form 

 of cylindrical casts. 



The most valuable contribution to our knowledge of the food of the 

 fresh-water fishes of the western United States has been made by Pro- 

 fessor S. A. Forbes, in Bulletins Nos. 2 and 3 of the Illinois State Labora- 

 tory of Natural History, for the years 1878 and 1880. With the most 

 painstaking care the results of a vast number of examinations are re- 

 corded. He finds that the Darters, Perches, Lahracida\ Centrarchoids 

 or sun-fishes, Scioenoids, Pike, Bony Gars, Clupeoids, Cyprinoids, Suck- 

 ers, Cat-fishes, and Amia, both the young and adults, consume large 

 numbers of small aquatic, and occasionally small terrestrial organisms, 

 uotably the smaller Arthropods. While many of the more voracious 

 species, both young and adult, feed on their immediate allies, the dietary 

 of the fishes of Illinois, according to this observer, includes Mollusks, 

 Worms, fresh- water Polyzoa, Hydrachnida?, insects of both mature and 

 and larval forms; Crustacea, embracing Decapods, Tetradecapods, Am- 

 phipods, Isopods, and Entomostraca of the groups Cladocera, Copepoda, 

 and Oscracoda ; Eotifera, Protozoa, vegetable matter, and Algae. In his 

 first paper he alf^o gives a list of the organisms found in the stomachs 

 and intestines of the Pirate Perches, Gasterosteidce, AtherinUkc, Cypriii- 

 odontida\ Vmbrida', Hyodontidcc, and Folyodontidce. Both are accom- 

 panied by elaborate comparative tables, and, in an economical sense, 

 are of the greatest practical importance in their bearing upon fish 

 culture. 



It has, however, been known long ago that fishes consume large quan- 

 tities of small Crustacea, as will be seen from the following extract from 

 Dr. Baird's work : 



" That the Entomostraca form a considerable portion of the food of 

 fishes has long been observed, and it is very probable that the quality 

 of some of our fresh-water fishes may in some degree depend upon the 

 abundance of this portion of their food. Dr. Parnell informs me that 

 the Lochlevin trout owes its superior sweetness and richness of taste 

 to its food, which consist of small shells and Entomostraca. The color 

 of the Lochlevin trout, he further informed me, is redder than the com- 

 mon trout of other localities. When specimens of this fish have been 

 removed from the loch and conveyed to lakes in other places the color 

 remains, but they very soon lose that peculiar delicacy of flavor which 

 distinguishes so remarkably the trout of Lochlevin. The experiment 

 has been repeatedly tried and always with the same results. The ban- 

 stickle {Gastrostevs tracliinus) devours them with great rapidity, and I 

 have seen two or three individuals clear in a single night a large basin 

 swarming with Daphinse and Cyclops, etc." 



The writer would also refer to articles on the food of fishes in the Reports 

 of the United States Fish Commission for 1872 and 1873 by Professors 

 Milner and Smith, and to papers by Widegren and Ljungman on the 

 Copepodan food of herring. Also a paper by Dr. C. C. Abbot in the same 



