Descriptions of New Fluviatile Shells. 



It is seldom that any of our Melanice are found inhabiting 

 waters so still as those of the small lakes so numerous in Stark 

 and the neighboring counties in Ohio ; nearly all the family 

 are denizens of rapid streams abounding with rocks, to which 

 they adhere, often in great numbers. Occasionally, however, 

 they attach themselves to the dead bivalve shells which pave 

 many of the rivers in our Southern and Western States, or 

 eling to the long grass which grows in them. 



This species was first published on the cover of Haldeman's 

 Monograph of the Fresh- Water Shells of North America, No. 

 4, December 28, 1841. A short time previous Mr. Lea had 

 published a species from Tennessee under the same name, 

 which publication I had not then seen. It becomes expedient, 

 therefore, to change its name to one not preoccupied, and I 

 propose, in re-describing the species, to confer upon it that of 

 " gracilior" which seems even more appropriate than the name 

 originally given to it. 



