166 Wisconsin Academy of Sciences^ Arts, and Letters. 



study. It Tvas in the ocean that the ancestors of our fresh water 

 animals dwelt, and it is amongst those animals that the student 

 may expect to find the most information in regard to the devel- 

 opment of life on the earth. 



But the lakes have their fauna, a fauna of great numbers if 

 not of great variety, and because of their isolation and somewhat 

 peculiar conditions, present a very interesting study in the dis- 

 tribution of animals. Of course the best known members of this 

 fauna are the fishes, whose numbers, habits, and food are fairly 

 well knoxvn. Fish are so important for human food that a study 

 of their habits comes to be a matter of commercial importance, 

 and our federal and state governments expend large sums of 

 money for this investigation and for the practical w^rk of rear- 

 ing and distributing spawn and young fish. In Wisconsin, 

 too, as well as in some of the other northern states, it is a matter 

 of great practical importance to maintain the numbers of game 

 fish in our lakes simply for the purposes of sport. Until one has 

 made the rounds of the summer resort lakes he has little idea of 

 the multitudes of people who come to our state in the summer 

 season, attracted largely by the opj)ortunities for fishing. Hun- 

 dreds of thousands of dollars are brought to us every summer 

 in this way, and it is a good business policy which leads us to do 

 all in our povv^er, and even spend large sums of money, if neces- 

 sary, to maintain our stocks of game fish. 



It has long been known, of course, that fish are dependent for 

 their food upon smaller animals, and it has also been known that 

 a knowledge of these same small animals was necessary to any 

 accurate and complete knowledge of fish, but this study was so 

 difficult and involved so much drudgery that for a long time it 

 was neglected. 



Anything like an exact knowledge of the Crustacea may be 

 said to date back only half a century to the ^vritings of Fischer 

 and Glaus, although some papers upon this subject had been 

 published previously. 



In 1817 Say published a somewhat extended article on the 

 Crustacea of the United States, in which he speaks of one 

 Ostracod. two Daphnias and one Cyclops^ as inhabiting the 

 waters of the southern states. In 1843, in the "Natural History 



