290 MICHIGAN SURVEY, 1908. 



var. sanctcemarice (Fig. 63, No. 2) but quite diflferent in the shape of the 

 spire. Variety C. (Fig. 63, No. 6) is the largest in cubic capacity yet 

 known from this country. It was found only in Siskowit Lake, whose 

 quiet waters and especially favorable conditions have conduced to the 

 production of this unusually fine, thin, inflated form. 



32.* Lymncea megasoma Say. 



Range: "Northern New England, Canada, and British America to 

 Lat. 57° N." (Dall). Also Northern Michigan, Wisconsin and Minnesota. 



Michigan: Isle Royale, St. Mary's River and Roscommon County. 



Isle Royale: IV, 3, Bayou at Tobin Harbor, No. 124, (Adams). A sin- 

 gle large, but dead, specimen was found in a pond-like bayou which was 

 connected with Tobin Harbor by a very narrow and short outlet. 



33. Lymnwa emarginata Say. 



Range: "Northern United States east of the Mississippi, Canada and 

 northward." (Dall). 



Michigan : Shores of the Great Lakes north of Saginaw Bay and some 

 inland lakes from Roscommon County northward. 



Isle Royale: I, 1, Lake and Bay Beaches, Nos. 24, 50, 57, 58, 59, 74, 

 118, and 125; 3rd Cove west of Camp on Light-house Peninsula, No. 7; 

 III, 4, Head of Sumner Lake Trail, (Wood) ;'V, 1, Beach at Siskowit 

 Bay, No. 200. 



This is a characteristic and abundant species along the lake beach 

 where it was found associated with var. B. of Lymnwa stagnalis. The 

 same form, but with a rather heavier shell, is very abundant along the 

 shore of Mackinac Island. Specimens from one rock pool, No. 58, are 

 peculiar in being longitudinally striped with white like Lymnwa reflexa 

 zebra Tryon. Those from another, Nos. 59 and No. 74, are unicolored. 



34. Lymnwa pilsbryana Walker. 

 (Nautilus, XXII, p. 4, PI. I, fig. 2, 8-11, 1907) . 

 Range: Isle Royale is the only known locality. 



Isle Royale: X, '04, Washington Harbor, No. 1 (Wood). This form, 

 so far as the collections show, is apparently confined to the west end 

 of the island. It was doubtfully referred to Lymnwa sumassi Bd. in 

 the Report Exped. 1904, p. 97. A larger suite of specimens from the 

 original locality in Wasliington Harbor was collected in 1905, including 

 a few full grown examples which confirm its specific distinctness. 



35.* Lymnwa oirussa Say. 



Range: "Northern United States and Northward." (Dall). 



Michigan : Generally distributed. 



Isle Royale : III, 2, Small Island in Rock Harbor, No. 89 ; III, 3, 

 Bulrush Zone at western end of Rock Harbor, No. 164. 



36.* Lymnwa catascopium Say. 



Range: "Northern United States to Rocky Mountains, Canada and 

 northward." ( Dall ) . 



Michigan : Shores of the Great Lakes and connecting rivers and lower 

 waters of tributaries in northern counties. 



Isle Royale: North shore of Rock Harbor, No. 110; III, 3, Bulrush 

 Zone at western end of Rock Harbor, Nos. 160, 163, 164; III, 6, South- 

 west Coves of Rock Harbor, No. 91 ; IV, 2, Island No. 14, Tobin Harbor, 

 No. 30 A; IV, 6, Small Island in Tobin Harbor, No. 123; V, 6, South 

 shore of Siskowit Lake, No. 220. 



