Occasional Papers of the Museum of Zoology 7 



23. LynuHva clodcs Say. — Chippewa: A young shell, 

 but apparently this species, of 2.5 whorls, 2.75 mm. x 1.15 mm. 

 The lip is thickened and the columella is heavily calloused. 



24. Lynincca lanceata Gld. — Schoolcraft: From a slough, 

 in leaves and weeds. These are typical in form and size, and 

 are eroded on the apices. 



25. Lynincca cniarginata Say. — Young shells from rocks 

 at the edge of the water, Mackinac Island. Abundant in this 

 locality (Walker, 1908, p. 290) and a representative of the 

 purely boreal element {Ibid., p. 282). 



26. Physa gyrina Say. — Schoolcraft: From submerged 

 leaves and grass in a wooded pool with sand bottom, in a 

 backwater from the river, from Buschwahr Creek, and from 

 Bear Creek. Almost all of the lots are immature shells. Alger: 

 One lot, from rushes in White Lake. Chippewa: From black 

 ash swamp, Vermilion ; from pond on the beach at Vermilion ; 

 and a variety with longitudinal stripes from Beaver Pond, 

 Vermilion. 



2y. Physa clliptica Lea. — Chippewa : A very large series 

 of several hundred specim.ens was obtained from a small spring 

 brook. Almost all are striped with white. 



28. Physa ancillaria crassa Walker. — Several specimens 

 were collected with Lymnaca emarginata Say from rocks at 

 the edge of the water, Mackinac Island. 



29. Physa sayii ivarreniana Lea? — Alger: From White- 

 fish River. Chippewa : Shelldrake River, Vermilion ; on lily 

 leaves and stems, Vermilion Lake ; shore of Lake Superior near 

 Vermilion ; pond on beach, Vermilion. 



This is the common form of Physa represented in the col- 

 lection. It has been difficult to refer these shells to any species 

 through the lack of any very distinctive characters. Very few 

 fully mature specimens are in the collection. 



