SUMMARY 



81 



abundant and evenly distributed throughout the deep-water belt. The 

 principal invertebrates are Pontoporeia hoyi, My sis relicta, water-mites, 

 midge larvae, and a species of Pisidium. 



The fish, however, show some noteworthy peculiarities of distribution. 

 The lake trout rarely leaves this belt, except during the breeding season. 

 The blackfin (Argyrosomus nigripinnis) is below 70 meters, except in 

 December, when it has been recorded in 60 meters. Hoy's whitefish 



Representative Crustaceans of the Deep-Water Community of 

 Lake Michigan 



Fig. 22. — A schizopod (Mysis relicta); enlarged as indicated (after Smith). 

 Fig. 23. — An amphipod {Pontoporeia hoyi) (after Smith). 



{Argyrosomus hoyi) is rare, and Triglopsis ihompsoni has not been 

 recorded above 115 meters; all accordingly live under uniform condi- 

 tions — no day, no night, no seasons. 



III. Summary 



The available data on the conditions and life in the lake are of such 

 a nature as to justify few conclusions of weight. We find only hints 

 here and there which may be useful to those who shall investigate the 

 lake in the future. 



1. Bottom forms are the most abundant on the open shores which 

 are rocky, and which form good substrata for the attachment of algae 

 and the holdfast organs of animals. 



