88 THE NAUTILUS. 



Clearwater Lake is a beautiful sheet of water. It is 10 or 12' 

 miles long, from a few rods to 3 or 4 miles wide, and very irregular 

 in outline. Over most of its bed it is pebbly or rocky and quite 

 shallow, many acres in its centre being less than two feet deep. The 

 surrounding timber is quite heavy, and furnishes good retreats for 

 land mollusks, while the maples, elms and oaks, by their abundant 

 shade, keep the soil somewhat moist. 



Belle and Heath Lakes, situated two miles west from Clearwater, 

 are small, deep, weedy and muddy, and are typical of several other 

 lakes visited, of which no further mention will be made. 



Their floors, at margin, are covered with fine, marly mud deposit, 

 and are heavily overgrown with rushes and white lillies. Beyond 

 the water's edge, the shores are boggy and overgrown with rank 

 grass. The surrounding country is rolling and sandy; timber, 

 scrub-oak, poplar, birch, and other small shrubby trees and to still 

 further render it unfit for molluscan habitation, it is frequently 

 overrun by forest fires. No shells were found away from the imme- 

 diate vicinity of the lakes. 



Land species were collected at the following stations: 



Station B. Belle Lake. Among grass roots on crowns of bogs, 

 unless otherwise designated. 



Station C. Clearwater Lake. Sifted from leaf-mould taken from 

 banks of small spring rill. 



Station I. Islands in Mississippi River at Clearwater. 



Station R. Rockford, Minn., 20 miles south of Clearwater. 



Station D. Drift in Mississippi River at Bellevue, la. 



Station E. Vicinity of Bellevue, la. 



Valuable assistance has been rendered in verifying and identify- 

 ing by Dr. Sterki. 



1 . Selenites concava Say. D. 



2. Pseudohyalina milium Morse. C. 



3. Pseudohyo/iiiii mintiscul.a Binn. It, under chips at water's 

 edge of Crow Creek. B, D. 



4. Zonitoides nitida Mull. C, under boards among the reeds at 

 lake margin. I, very abundant under fine bark chips at water's 

 edge. E, crawling among weeds near creek. 



5. Vitrea radiatula Aid. Common at 15 and C. 



6. Vitrea, radiatula Aid. (albino), very closely resembling H. 

 binneyana. A beautiful variety found at both B and C, together 

 with the typical specimens. 



