BnJcer — Notes on a Collection of Mollusks. 9 



acuteness of the spire and in the length and width of the 

 shell. It is a triannuan, the three rest periods showing as 

 white varicose bands. Walkeri is related to Integra but has 

 a longer spire and less rotund whorls. Some characteristic 

 measurements are as follows : 



Length 11.00; width 7.00; aperture length 7.50; width 3.50 mill. 

 " -11.00; " 6.00; '« " 6.50; " 3.00 " 



" 11.00; " 6.50; " •' 6.50; '< 3.00 " 



Walkeri was described from specimens collected at 

 Petoskey, Michigan. 



Family Lymnaeidae. 



Segmentina aemigera Say. 



Stony Point; Sugar Island. Very common. 



Planorbis binneyi Try on. 



Sulphur Island; Thunder Bay River; Mill pond, Alpena. 



This large, course species is widely distributed, ranging 

 from New York to Washington. It has a superficial resem- 

 blance to Planorbis corpulentus, but lacks the peculiar trun- 

 cation of the spire whorls and the angular shoulder of the 

 whorls, besides having other differences. Binneyi is also 

 abundant in the St. Lawrence River, at Wellesley Island. 



Planorbis bicarinatus Say. 



Ox Bow; Alpena. Typical and common. 



Planorbis bicarinatus striatus Baker. PL I., tig. 11. 



Long Lake. 



About 50 specimens of this variety are before me. The 

 spiral lines are notably distinct, much more so than the fossil 

 type specimens from the Pleistocene deposits at Milwaukee, 

 Wisconsin. In some specimens the spiral lines are deeply 

 incised. The uniformity of the present material and the 

 general absence of spiral lines on typical bicarinatus from 

 this locality, would seem to indicate that striatus is a good 



