138 THE AMERICAN MIDLAND NATURALIST 



A * 7 Gammaridae. 



B 13 Gammaridae. 



C 14 Gammaridae. 



From a piece of chara the same size: 



A. 3 Gammaridae. 



' B 4 Gammaridae 



C 4 Gammaridae. 



The moss seemed to be the most desirable. The gray colored type 

 which is the larger was found, as a rule, nearest the shore. These 

 Gammaridae also live near the surface. Other forms found were 

 earthworms, snails, Asellus (few) and Hydrophilous beetles (few). 

 In the protected place along the shore a great many Physa were 

 found on the algae. 



On another lump of moss the size of the hand we found 2 1 

 leeches, 5 snails, 2 earthworms, i beetle, 10 Gammaridae . 



From the preceeding data we drew the following conclusions: 



1. Life scarce, due to lack of oxygen. 



2. Gammaridae most numerous of forms found, being most 

 alundant near the surface and in the plant life along the shore. 



3. Algae and moss plentiful, furnishing abundant food for 

 plankton. 



Towings were taken at the surface (Tw. i); (Tw. 2) }i the 

 distance to the bottom and in these the following forms were found: 



Tw. I . 

 Diatoms (abundant). 

 Spirogyrae (sparse). 

 Blue-green algae (abundant). 

 * Roundworm (Nais I ). 



All smaller protozoans absent. A few Desmids foimd. 



Tw. 2. 

 Spirogyrae (sparse). 



Cypris 4. 



Annulates 3. 



Insect larvae 2. 



On August 3rd. we took the following readings, the carbon 

 dioxide content being taken alDOut 10 feet below the surface: 



Reading No. i 50 c. c. per M. 



Reading No. 2 60 c. c. per M. 



Reading No. 3 60 c. c. per M. 



The depth of the water near the log on the west side is 32 feet. 

 The depth in the depression on the east side is 29 feet. 



