1893,] Mollusks of Louisiana. 961 
some of the hills. These mosses are fed by springs. In small 
holes over this moss hundreds of this Pisidium can be collected 
by pulling up the moss and other aquatic or semi-aquatic 
plants and examining their roots. 
SPHJERIUM. 
Spherium contractum Prime, in the ponds and creeks around 
Jonesville, Texas, and in Cross Lake, near Shreveport. 
Spharium fabale Prime, in nearly all of the smaller streams of 
northwest Louisiana, and is often found in the greatest abund- 
ance. It is the most common species of the genus in the sec- 
tion. : 
Sphærium transversum Say.  Dorcheat Bayou and Lake Bis- 
teneau. 
There are, undoubtedly, many other species of the Cyrenidæ 
in the section. We have collected immature examples of other 
species, but there is too much doubt attached to their identifi- 
cation to justify entering them on this list. 
Cambridge, Mass., July 16, 1893. 
