32 THE NAUTILUS. 



Elimia virginica var. muUilineata Say. Cayuga Lake. 



Bythinia tentaculata Linn. Cayuga Lake, Seneca River at 

 Waterloo. 



Bythinella attenuata Hald. Chautauqua Lake. 



Byihindla nickliniana, Lea. Chautauqua Lake. 



Amnicola granum Say. Chautauqua Lake. 



Amnicola limosa Say. Cayuga, Chautauqua, Cayuta Lakes. 



Amnicola lustrica Pilsbry. Cayuta Lake. 



Amnicola pallida Hald. Chautauqua Lake. 



Valvata sincera Say. Cayuga Lake. 



Valvata tricarinata Say. Cayuta, Chautauqua, Owasco Lakes. 



Vivipara contectoides Binney. Cayuga Lake. 



Campeloma decisa Say. Cayuga, Canandaigua, Conesus, Chau- 

 tauqua Lakes. 



After making this collection from the shallow waters of the 

 lakes, the question naturally arose whether a deep-water mollus- 

 can fauna exists in Cayuga Lake. 



To determine this, Professor G. D. Harris and the writer 

 aided by Dr. Pilsbury, now of Ann Arbor University, made 

 three dredgings from east to west across the lake between the 

 Ithaca Lighthouse and Estey's Glen. A United States Fish 

 Commission dredge, weighting about fifty pounds, with a net 

 attached was employed. As the dredge was worked by hand 

 power with a windlass, it was not feasible to go below about 

 200 feet. The maximum depth of Cayuga Lake is about 450 

 feet. This deep is in the middle of the lake at a point north- 

 east of Toughannock Point (formerly known as Goodwin's 

 Point), some miles north of our furthest section. 



These dredgings proved very conclusively that molluscs are 

 abundant from the shore line to about ten feet, after twenty-five 

 feet they become very scarce, the dredge yielding only a few 

 Amnicolas and broken fragments of shells, the occupants having 

 apparently been preyed upon by fishes. 



In the greater depths no signs of mollusca or of plants were 

 found. There was only a very fine grey mud entirely barren 



of life. 



We believe this to be due partly to the great depth of the 



Finger Lakes; but much more to the extremely low tempera- 



