Descriptions of New Fluviatile Shells. 



various, and often so obscure, as to increase this difficulty. 

 Many of them, in fact, are unhonored with a name, being mere 

 springs, sometimes scarcely a foot wide, and a few inches deep. 

 The abundance of this form of animal life in this part of the 

 world, not only in species, but also in individuals, is inconceiv- 

 able to those accustomed to its paucity in the Eastern States. 

 In Kentucky, Tennessee, and Georgia, no running water is too 

 insignificant to be altogether devoid of shells. Among these, 

 Melanioe are strikingly abundant ; and, indeed, so far as noticed, 

 they were almost the sole denizens of the small streams. I can- 

 not recollect having seen a single specimen of Limncea or 

 Physa in all the route. Only two or three species of Paludina, 

 no Planorbis, perhaps two species of Cyclas, and only one Ancy- 

 lus (A. elatior nobis), a new species from Green Eiver, Ken- 

 tucky. 



The most prominent streams examined were Green Eiver, 

 Barren River, Beaver Creek (a branch of Barren), JSTolen River 

 (a branch, I believe, of Salt River), all in Kentucky ; and in 

 Tennessee, the Cumberland River, Cany fork of Cumberland, 

 Collins River, Rock River, Defeated Creek, Battle Creek, 

 Chattanooga Creek, Holston, French Broad, Tennessee River, 

 Mine-lick Creek, and Sequatchee River; while in Georgia, 

 the Ochmulgee, Chattahoochie, Etowah, Coosa, Oostanulla, 

 Connesauga, Sumac Creek, and Rock Creek, were examined, 

 and in all these States, hundreds of smaller streams, of every 

 grade, tributary to those I have mentioned. 



My means of carriage being limited, but little time was 

 devoted to any one stream, as a few minutes only sufficed to 

 gather two hundred specimens of each species. Generally 

 not more than three species were found in these small 

 streams at any one point, and to gather four or five hundred 

 specimens, twenty minutes was ample time. Every stone in 

 these streams, every piece of floating wood, and, where both 

 were absent, even the muddy bottom, was covered by Melanias, 

 and I only had to strip them off with my hands, and select 



