514 NATURAL HISTORY OF AQUATIC ANIMALS. 



discovering correctly the character of their food. On opening the stomachs of numerous White- 

 fish lie at first failed to determine the character of the stomach contents, until, after wash- 

 ing the half-digested mass in a basin of water, he found the sediment to be full of small Crus- 

 tacea, whose existence in the lake had never before been suspected. My examination and pre- 

 servation of the stomach contents from all quarters of the Lakes confirmed Dr. Hoy's observa- 

 tions, and discovered a few other small forms of life as the food of White-fish. The invertebrates 

 found were of crustaceans : species of the families Gammarida; and Mysidcc ; of the mollusks : 

 species of the genus Pisidium ; and certain insect larvse. A few fish-ova were frequently found 

 in the stomach, and it was not unusual to find a little gravel. 



"In the greater portion of the lake the Gammaridce constituted the principal food. In shallow 

 regions small Conchifers were more numerous. At Point aux Barques, on the north shore of Lake 

 Michigan, where a very large type of the White-fish was found, the stomach contents were entirely 

 of the Mysis relicfa Loven. In the Sault Ste. Marie Rapids, in July, a mass of small chrysalides 

 was found in the stomachs of a number of White-fish. In October, from the same locality, the 

 larvae of the caddis-fly were found in the stomachs, apparently carefully separated from their 

 artificial coverings. Stomachs opened in Lake Superior contain principally the Mysidce. At 

 Rocky Island, in the northwestern part of Lake Michigan, a vessel with a cargo of wheat was lost 

 a few years ago. The fishermen say that White-fish were taken in that vicinity for several years 

 afterward with wheat in their stomachs. 



"Rarely White-fish will take a bait. The breakwater protecting the Illinois Central Railway 

 at Chicago was formerly a favorite fishing place, and in early summer was often lined with a row 

 of boys and men fishing for perch. There was seldom a day passed but that a few White-fish 

 were taken. Mr. Trompe, of Sault Ste. Marie, has frequently taken them in that locality with 

 a hook baited with a May-fly, Epliemeridce. At a fishing dock on Sand Island, one of the group of 

 the Apostle Islands, Lake Superior, there were a few taken this season with a worm bait. 



" The leech, Ichihyobdella punctata, Smith, parasitic on the Wfeite-fish, and numerous in some 

 localities, was in no instance found in the stomach. This corroborates Dr. Hoy's observations. 

 A similar fact was noticed afterward at Detroit River. A parasitic crustacean, a Lerncea, was 

 found adhering to the White-fish in numbers, and, though many stomachs were examined, in no 

 instance were any of the parasites found in the contents. Both the Lerncea and the Ichthyobdella 

 are related to species made use of as food by the White-fish, as near in the one instance as being 

 in the same class, and the other in the same order. The mouth is constructed for nibbling along 

 the bottom, the opening being directed nearly downward, and they gather in the small life of the 

 bottom and the gravel as they move slowly along. 



"Dredging in the lake at different localities and examination of stomach contents at numerous 

 points prove that the crustaceans and the mollusk constituting the principal food of the White- 

 fish are distributed throughout the lake bottom, in all localities, and at all depths over about 

 twenty fathoms. In Torch Lake, a deep inland lake in the Grand Traverse region, Michigan, 

 where a large type of White-fish is found, the dredge brought up the same species of crustaceans 

 and mollusks as were found in Lake Michigan. The failure to find food in the stomachs of White- 

 fish has frequently resulted from the fact that the fish examined were taken from the pound-nets, 

 where they had remained long enough to digest the contents of the stomach before they were 

 taken from the water. Fish from the gill nets have generally the food in the stomach only 

 partially digested, while a hundred fish in succession from the pound-nets may be opened and 

 every stomach found empty. 



It is frequently asserted that aquatic vegetation afforded sustenance to the White-fish. The 



