12 University of Michigan 



are marked (m = marlj in the list of species (Table 1). 



Habitat 7. Betiveen Lakes. Upper and Lower Lakes are 

 connected by a channel a few rods wide, about 10 feet long 

 and about 4 feet in depth. A quite considerable current keeps 

 the coarse sandy bottom free from muck. Valisneria spiralis 

 was practically the only conspicuous plant in the channel itself, 

 but in the quieter water at either end Potamogeton zosterifo- 

 lius and P. amplif alius were quite abundant, and there were a 

 few plants of Polygonum amphibium. In addition, the water 

 lilies of Habitat 4 were numerous in the close vicinity. Many 

 of the specimens were dead and chalky; these are marked (m) 

 in the species list (Table I). 



Habitat 8. South Shore. In shallow water along the south- 

 west shore near the outlet into the East Branch, a very per- 

 ceptible current prevents the accumulation of much muck on 

 the sandy bottom. In water less than 12 inches in depth the 

 sand is quite bare, but beyond that depth some muck was held 

 by a dense bed of Valisneria with a scattering- zone of Pota- 

 mogeton amplifolins and P. zosterifolius along its outer edge. 

 This habitat is characterized by a number of species of uniones 

 and by the abundance of Campeloma decisiim. 



Taiiiarack Lake 



Habitaf p. Tamarack Lake and Outlet. Tamarack Lake 

 had apparently been considerably larger at one time, as it is 

 surrounded by extensive tamarack-alder swamps. However, 

 it has reached a late stage in its life history and has become 

 smaller and very shallow, with a soft, mucky bottom com- 

 posed of decaying plant material. When studied it was cov- 

 ered with the pads of the white and the yellow water lilies, 

 and surrounded by a sedge flora instead of the usual sphag- 

 num bog. For some distance below its source the small creek 



