Descriptions of New Fluviatile Shells. 81 



our Western streams and rivers abound. The journey was 

 extended as far as Macon, in Georgia, when heavy and con- 

 tinuous rains arrested further progress, by swelling the streams 

 so high as effectually to debar all collecting. From the unusual 

 fulness of most of the other streams visited during the journey, 

 the number of Naiades obtained was restricted, but large quan- 

 tities of Melanidce were collected. Some of these were of old 

 and well known species; others represented species which, 

 though already named and described, are as yet little known 

 in collections, or have been described from solitary or imperfect 

 examples. The species named and characterized in the follow- 

 ing pages, with others to appear hereafter, consist, for the most 

 part, of the new acquisitions made during this journey. 



The author regrets his inability to give a more precise state- 

 ment of habitat than that here assigned to most of his species ; 

 but the precautions he had taken for keeping his collections 

 distinct proved insufficient, and he, therefore, prefers to merely 

 name the State in which they were taken, — viz. Kentucky, 

 Tennessee, &c, — rather than misstate the stream where found. 

 The waters from which the specimens were collected were so 

 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, 

 Melawice 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 Pahtdina, 

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

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

 tucky. 



