190 THi: CHICAGO ACADEMY OF SCIENCES. 



Bay; French River; Lake Xipissing; Lake Temagami and Lake Tcmiskaming, 

 Xipissing Dist.; '•doubtless occurs in suitable waters from Albany River to 

 Lake Abittibi" (Latchford) ; Cobalt Lake, Xipissing Dist < Latchford). 



Quebec: Nun's Island, near Montreal, Hochelaga Dist. (AYhiteav 

 McGoey's Lake, in the Laurentides, near Chelsea (Trans. Ottawa Xat. I-'ield 

 Club).' 



Geological Range: Leda clay, ten miles below Ottawa City, On- 

 tario i Belli. 



Ecology: In rivers, lakes, sloughs and ponds. "A small lily 

 pond in the bed of the Mississippi River just below St. Cloud. The 

 snails are to be seen floating on the surface or feeding upon the lily 

 leaves. They are shy, sinking almost instantly when alarmed" (Sar- 

 gent i. "The animal is sluggish in its habits and excessively timid, the 

 slightest disturbance of the water causing it to instantly draw itself into 

 the shell. Though it feeds upon algae in confinement my specimens 

 also devour the animals of land snails and of fresh-water mussels with 

 great greediness'' (Wetherby). ''Common in ponds and pools" 

 (Keyes). "Not uncommon on floating masses of vegetation in some of 

 the ponds and lakes in the northern part of the state" (of Iowa) 

 (Shimek). '"The waters of Lake Cobalt, Ontario, Canada, are so im- 

 pregnated with arsenic as to cause serious intestinal trouble to those 

 who use it. L. mcgasoma, however, lives and thrives, attaining large 

 size and preserving to a ripe old age the beautiful epidermis character- 

 istic of young shells" (Latchford i. 



At Tomahawk Lake, Wisconsin, mcgasoma lives in swampy por- 

 tions of sheltered bays where the water is quiet. The bottom of such 

 a habitat is boggy and the water is so shallow that frequently little 

 boggy islands are formed, and on these mcgasoma may be found, one 

 or two specimens on each island. In other parts of this habitat they 

 may be found near the shore, clinging to logs and other debris. A 

 small, swampy slough, lying between the Wisconsin River and Gil- 

 more Creek, Oneida County, afforded the best habitat for mcgasoma, 

 where they lived in considerable number. This slough is about a quar- 

 ter of a mile long and two or three hundred feet wide ; the water is (in 

 summer) but a few inches in depth, but the mud, which is about the 

 consistency of mush, is from six to ten feet in depth. Mcgasoma lives 

 on the surface of the mud and on old logs which the lumbermen have 

 left in the swamp. It would seem that the characteristic habitat of 

 mcgasoma is a swamp or marshy pond or bay (Baker). 



A single large, but dead, specimen was found in a pond-like bayou 

 which was connected with Tobin Harbor by a very narrow and short 

 outlet (Walker, Isle Royale). 



