Distribution, Food and reproductive Capacity of some fresh-water Amphipods 3 



found in small numbers along the lake margin and in the mouths of 

 the tributaries wherever vegetation exists. It is very scarce at a dis- 

 tance of eight or ten rods away from the lake. As the season ad- 

 vances, its distribution is extended so that by the first part of August, 

 it is exceedingly abundant throughout the cove and the adjoining pro- 

 pagating ponds of the Biological Field Station; in the Fall Creek to 

 the beginning of rapid water, a distance slightly greater than one- 

 eighth of a mile from the lake, and up the Cayuga Lake Inlet to a 

 point approximately one-fourth of a mile distant from the lake. From 

 this time until after the ice appears it is the most abundant amphipod 

 wherever found. 



It seems to occur in greatest abundance where vegetation is thickest 

 and is associated with thick masses of Marsilea, Elodea, Potamo- 

 geton, Myriophyllum and Utricularia. That it occurs abundantly 

 in certain parts of the Montezuma Marshes at the north end of Cayuga 

 Lake, is indicated by the presence of seventy-two individuals in the 

 enteron of a king eider duck taken there November 26, 1909 (Embody, 

 1910). Warm water does not seem to bar its distribution since it 

 occurs and breeds in the waters of the "Cove" where the temperature 

 becomes as high as 30® C. This species does not occur in the isolated 

 pools of Renwick Marsh and I am unable to account for its absence 

 unless the drought of summer and the frost of winter kill off those 

 which may have entered during floods, before they have had a chance 

 to multiply sufficiently to be detected. 



The writer has not yet been able to locate individuals of Gam- 

 maruslimnaeus in Ithaca waters. It in stated that the New York 

 Forest, Fish, and Game Commission (Report for 1897) placed five thou- 

 sand from Caledonia Creek into the waters of Six-mile Creek above 

 Ithaca in 1896, that these might propagate and furnish food for brook 

 trout. 



The species occurs very abundantly in a trout brook near Auburn, 

 N. Y. and at this place the writer was able to gather a few notes 

 upon its distribution. It seems to occur in greatest numbers near the 

 head-waters of the brook and its tributaries, and even in the springs 

 themselves^). The largest numbers were found associated with the 

 roots of the water cress, thick tangles of Chara and under decaying 

 leaves. No individuals were found in pools well down the brook where 



^) The yearly range of temperature in the upper part of this brook is from 

 6«— 12<> C. 



