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Description of a new species of NERITINA, from Coosa Rivei , Alabama. 



BY ISAAC LEA. 



(Read February 12, 1861.) 



P 3 3~~ 1 ft Neritina Showalterii. — Testa lsevi, rotundata, diaphana, luteo-cornea ; 

 spira. valde 1 depressa ; suturis leviter impressis ; anfractibus trinis, inflatis ; 

 apertura semirotunda ; labio dilatato, albo, incrassato, edentulo etincurvato ; 

 labro dilatato, tenui, margine acuto. 



Operculum . 



Bab. — Coosa River, ten miles above Fort William, Shelby Co., Alabama. 

 K. R. Showalter, M.D. 



Remarks. — The discovery of this shell by Dr. Showalter marks the first notice 

 of the genus Neritina being observed in our fresh waters. His very close 

 observation and active investigation of the waters of central and northern 

 Alabama, have enabled him to lay the naturalists of this country under many 

 obligations by new discoveries, and this is certainly one of much importance. 

 We now see for the first time that this genus, which is common in Europe, 

 Africa, Asia, South America and the West Indies, also inhabits our southern 

 fresh waters. I have great pleasure in naming the species after the discoverer. 



This species is not closely allied to any which has come under my notice. 

 It is more rotund than usual, has a clear horn-colored epidermis, smooth and 

 shining ; the substance of the shell so thin as to permit the column to be visible 

 through it. 



It is to be regretted that among the four specimens sent to me by Dr. Sho- 

 walter, neither had an operculum. The soft parts of the animal have not yet 

 been observed. 



