246 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



are of tlie greatest practical importance in tlieir bearing upon fisli 

 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 consists of smaU shells and Entomostraca. The color 

 of the Lochlevin trout, he farther 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 baustickle 

 [Gastrosteus trachurus] devours them with great rapidity, and I have 

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

 ing with Daphnise and Cyclops, &c." 



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

 of the United States Fish Commissioner 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. 0. Abbot in the same 

 report, for 1875 and 1876, on the winter habits of the fishes of the Del- 

 aware. Mobius has found i^eces of algse, besides shells, snails, crabs, 

 and fishes in the stomach of the cod. The writer has found the stomach of 

 the sheep's-head filled with the remains of the shells of mussels and large 

 quantities of the slender branches of the common bright red S])onge,Micro- 

 cionaproliferiim, bitten off in short fragments by the incisor-like teeth 

 of the fish, and with the red sponge sarcode partly digested out of its 

 skeleton. It is presumed that the sponge feeds upon protozoan life, 

 and on account of its peculiar dentary armature the sheep's-head is 

 singularly well fitted to pasture upon sponges aud thus indirectly ap- 

 propriate protozoa as nourishment. The same remark applies to the 

 molluscan food of this fish. 



In young shad from Capehart's fishery, Albemarle Sound, said to have 

 been three weeks old, I found the remains of a number of adult Tipuli- 

 (ke, or crane-flies, in the intestine. This reminds me that in examining 

 the larvae of crane-flies some years ago, I was struck with the fine comb- 

 like fringes which garnish the edges of their wide oral appendages, and 

 which are so extended in life when the larva is in motion as to constitute 

 a sort of basket which opens downwards and forwards apparently to 

 strain out of the water the small organisms which constitute its food. 

 Here again we have young shad feeding upon an arthropod which has 

 passed its larval existeuce, feeding in great part upon protozoa. West- 



