Occasional Papers of the Museum of Zoology 9 



amcricatia disputed that dominance below the surface, but 

 Myriophylliim spicatiim was not very abundant. On the other 

 hand, Myriophylliim spicatiim, Ceratophylliim demersum and 

 Bidens hcckii predominated in the inner zone and the species 

 characteristic of the outer zone were not prevalent. Addi- 

 tional species of the inner zone were Potamogeton amplifolius, 

 P. ::ostcraefoliiis, P. filiformis and P. natans, the last being 

 the most abundant. Usually near the inner edge of the vege- 

 tation Pliilotria canadensis and Chara often occurred in con- 

 siderable patches, each forming a distinct island from which 

 other species were apparently excluded. 



No similar division of the moUuscan fauna into zones was 

 noticeable. In addition to the species found in the weeds 

 themselves, Anodonia inarginata was dredged from deep 

 water just beyond their outer edge. Also a single dead speci- 

 men of Lymn<ra megasoma was found on the Sturgeon River 

 flats below the lake ; this also was probably from the central 

 portion of the lake (Table I). 



Habitat 2. Water Lilies. Patches of water lilies, mostly 

 Nymphcra adrena, but with a few Castalia odorata, were scat- 

 tered throughout the inner two zones, but were especially 

 abundant in the Lower Lake, near the straits between it and 

 the L'pper. These plants formed distinct islands as appar- 

 ently no other plants are able to grow among them, probably 

 on account of their large leaves. 



The inner zone of Brown Lake, as mentioned above, reached 

 from the shore out to about 17 inches of water. This very 

 variable zone differed so much in the various parts of the 

 lake that it was divided into three habitats. It was wider 

 where the shore was firmer and sandy and had either a sandy 

 marl bottom as along the southern portion of the west shore 



