THE NAUTILUS. 19 



under which they grow, should be carefully studied. In order to do 

 this much more good material is needed from all over the continent. It 

 is very desirable to collect repeatedly, throughout the year, at favorable 

 places, wherever there is an opportunity for doing so; it is essential to 

 have the date of collecting with every lot, notes on the nature of the 

 habitat, and last but not least, to have good numbers of specimens, 

 not only the large ones, but also the half- grown and young. Any 

 material, from anywhere, will mean a contribution to our knowledf e. 



It may be added that the simplest and best means for collecting 

 small fresh-water mollusca, Sphoeriidae and gastropods, is a sack net 

 of good burlap on a frame of strong wire (i-| inch), the ring of 

 about 6-8 inches diam., tied to a handle of suitable length, e. g., a 

 broomstick. In this net mud and other material, scooped up from 

 the surface of the bottom, is washed, the coarser things gradually 

 removed; the remainder is taken home and dried well, but not in too 

 great heat. Then, a small sieve, e. g., a strainer, or several of dif- 

 ferent mesh measures, are very serviceable for separating finer and 

 coarser material, and it will be much easier to pick out the speci- 

 menSf of which the smallest should not be overlooked; some Pisidium 

 are not larger than 1 to 2 mm. when mature. Specimens to be sent 

 for examination are best left mixed up, or separated only for con- 

 siderable differences of size. The washings and specimens must be 

 handled carefully, especially Musculium^ since most of them are very 

 fragile. The whole " stuff," dirt and all, fresh or dried, may be sent 

 for examination, after the coarser materials are removed. 



For deep water a drag-net or small dredge of burlap will do good 

 service, especially if protected by an outer sack of strong canvas with 

 the bottom left open. It is very desirable that collecting be done in 

 lakes and deep rivers. 



DESCEIPTION OF A NEW FOSSIL LYMNiEA. 



BT F. C. BAKER. 



Lymn^a nashotahensis n. sp. 



Shell elongated, somewhat pyramidal; surface dull, growth-lines 

 conspicuous, crossed by fine, impressed spiral lines; whorls 6-6^, 

 rather rapidly increasing in diameter, flatly rounded, the body whorl 

 very large and quite convex or even gibbous; spire broadly pyramidal 

 or conic, longer than the aperture ; sutures well marked ; aperture 



