(83) 



The remarkably developed gill-rakers of this species thus receive their 

 explanation. These are very numerous and fine, arranged in a double 

 row on each gill arch, and are twice as long as the filaments of the gill. By 

 their interlacing they form a strainer scarcely less effective than the fringes 

 of the baleen plates of the whale, and probably allow the passage of the fine 

 silt of the river bed when this is thrown into the water by the shovel of the 

 fish, but arrest everything as large as a Cylops. The fish is said by the fish- 

 ermen to plow up the mud in feeding, with its spatula-like snout, and then 

 to swim slowly backward through the muddy water. Its mouth, it may be 

 noticed, is very large, even for a fish. 



It is possible that this wholesale destruction of entomostraca may affect 

 the food supply of other and more valuable fishes, especially of the very 

 young of the predaceous species. We cannot yet say, however, where the 

 stress of the struggle comes in the life of any given species, and conse- 

 quently are unable either to relieve or heighten it at will, or to perceive 

 the full effect of the forces already at work. Fuller knowledge must pre- 

 cede any but the most cautious and conservative recommendations. 



RECAPITULATION. 



A summary of the leading facts presented in this paper is given in the 

 following table. The figures taken from left to right give, in a general 

 way, the food of each family and species, and taken vertically show the 

 fishes which eat any given kind of food. The line of totals will show some- 

 thing of the relative importance to fishes as a class of the different food ele- 

 ments. The figures in the table have the same use as those in the preceding 

 list, showing the number of specimens of the given species found to eat the 

 food mentioned at the head of the column. 



It will be seen that, estimated in this way, the most important kinds 

 of food are insects, Crustacea, plants, fishes and mollusks, in the order 

 named. These data apply entirely to adult fishes, however ; if the young 

 were also taken into account, crustacean food would doubtless be found 

 more important. 



The best food fishes ("fine fish" of the markets — Percidae, Labracidae, 

 Centrarchidae, Esocidae) are chiefly piscivorous, except the Centrarchidae, 

 which are nearly omnivorous, but prefer insects. Scarcely any fishes ex- 

 amined, except some Cyprinidae, can be called strictly herbivorous, al- 

 though the gizzard shad (Dorosoma) is chiefly so, the animal food taken be- 

 ing probably incidental. 



That the sheepshead, with its enormous crushing pharyngeals, should 

 eat fewer mollusks than the red-horse, was scarcely to be expected, and may 

 yet prove untrue. 



Cat-fishes are the only ones shown to be scavengei's. The fishermen, 

 however, attribute similar habits to sheepshead and buffalo-fish. 



Cyprinidae seem to be divided into two sections, corresponding to the 

 shapes of the pharyngeal teeth, those without raptatorial hooks being her- 

 bivorous. 



All these general statements ought, perhaps, to be put in the form of 

 questions for future solution, since the number of specimens is too small and 

 the space and time represented too limited to justify settled conclusions. 



