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Art. VI. — New Melanidce of the United States. 



By Isaac Lea. 



During the past and present years, I have read several papers describing new 

 species of Unionidce and Melanidce kindly sent to me by E. E. Showalter, M. D., 

 of Uniontown, Alabama, a correspondent of our Academy, who has been unre- 

 mitting in his exertions to make known the natural history of that part of the 

 State. In those papers there were but few species of Melanidce. They were 

 purposely delayed with a view to bring them as much together as possible, and 

 the present paper will exhibit here the vast expansion of zoological life in this 

 Family, — the Coosa River really appearing to be the zoological centre of this 

 particular group. The great variety of form, color and size will at once strike 

 the naturalist, and he will be surprised in the examination of those forms to 

 observe how very few there are of tuberculate or folded species, which so well 

 characterize the members of the same Family in streams which form the Ten- 

 nessee and Cumberland Rivers at no great distance. It will also be observed that 

 Dr. Spillman, another of our correspondents, has contributed much to these papers, 

 from other sources, as have also many other friends. 



Family MELANIDCE. 



Genus GONIOBASIS.* 



Testa vel oonica vel f'usiforini. Apertura subrhomboidea, interne subangulata. Columella superne 

 interduni incrassata. Operculum corneuni, ad spirans pertinens.'f 



In my paper on the genus Trypanostoma, proposed by me (Proc. Acad. Nat. Sci. 

 1862, p. 169), I mentioned the importance of eliminating as many species as possible 

 from the genus Melania, which is so enormously extended as almost to prevent the 

 possibility of finding suitable names for the species. In the Proceedings of the Aca- 

 demy, Dec, 1861, I stated that Prof. Haldeman's genus Lithasia formed a very excel- 

 lent group. In working up a very large number of the family Melanidce, obtained 

 from the Southern and Western States, I have, notwithstanding the divisions which 

 had been made, found myself embarrassed with that form of aperture which is quite 



*Tmia., angle, and /?*«c, base. 



t This genus may be divided into two groups, one embracing the conical, the other the fusiform species. 



and these into smooth, plicate, carinate, &c. 



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