VI 



FRESH-WATER ANIMALS 



I PROPOSE to speak this evening about the fauna 

 of fresh-water ponds and streams, a subject of very 

 special interest to the members of the Society, 

 many of whom have a far more intimate and accu- 

 rate acquaintance with special groups than I can 

 either claim or reasonably hope to possess. Still, 

 there are some points of general interest which 

 may have escaped the observation of those who 

 have chiefly concerned themselves with one or two 

 particular groups ; and it is with regard to these 

 more general conclusions that I propose to speak 

 to-night. 



As regards geographical distribution the entire 

 animal kingdom may conveniently be divided into 

 terrestrial and aquatic forms, and the latter again 

 subdivided into those that live in the sea, and 

 those inhabiting fresh water. The marine fauna 

 is infinitely more abundant, and includes a far 

 greater number of species than that found in fresh 

 water ; and we can hardly be surprised at this. A 



