Occasional Papers of the Museum of Zoology 23 



itself. Near shore, in about one foot of water, the bottom is 

 usually composed of fine gravel intermixed with sand, although 

 in places there are slight deposits of organic material, twigs, 

 bark, etc. Practically no vegetation was present. 



Habitat j^. Deeper Water in the Bast Branch. The uniones 

 were the prevalent forms of the deeper waters of the Sturgeon 

 River and were abundant throughout the vicinity of Brown 

 Lake. However, a portion just below Brown Lake was most 

 thoroughly studied, as here the shells were very numerous and 

 collecting was facilitated, as the locality was near the camp 

 and was used for bathing. Here the water contained little 

 sediment, as it had just passsd out of the lake, but had the 

 characteristic reddish tinge already mentioned. The water 

 was about five feet deep and bore little vegetation, except zones 

 of Vaiisneria spiralis and Myriopliylhtin spicatnui along the 

 sides. I 



Menominee River 



Habitat S4- Twin Falls. Just below the Upper Twin Falls 

 of the Menominee a sandbar separates a small channel, about 

 30 feet wide and 8 feet deep, from the main river. The rocks 

 forming the shore are coated with a finely-divided deposit con- 

 taining considerable iron, and small pockets of sand occurred 

 in the hollows. Most of the univalves were obtained from 

 the rocks themselves, but the Sphaeriidae and Campeloma 

 decisum were partially buried in the sand pockets. 



Habitat 55. Sand Portage. The falls at Sand Portage are 

 about six feet in height, and have a considerable extent of 

 rapids above and below them. In the backwaters below the 

 falls the current is almost imperceptible along the shore, and 

 the outcrops of Quinnesec schist, which forms the bed and the 

 shores of the river, are coated with a deposit of algal material 

 considerably encrusted with iron. 



