NATURAL SCIENCES OF PHILADELPHIA. 55 



quadro-vittata, ad basim eanaliculata et reeurvatfi ; columella sigmoidea, su- 

 perne incrassata; labro subconstricto, margine acuto. 

 Hab. Coosa River, Alabama. E. R. Show-alter, M. D. 



Lithasia imperialis. Testa tubereulata, fusiformi, subcrassa, tenebroso- 

 cornea; spira elevata, conoidea ; suturis irregulariter et valde impressis; an- 

 fractibus senis, ultimo subgrandi, superne irregulariter tuberculatis, subinfla- 

 tis; apertura parviuscula, elongato-rhornboidea., intus albida, fuscis capillaris 

 instructis, ad basim eanaliculata et recur vata ; columella sigmoidea, superne 

 paulisper incrassata; labro subexpanso, margine acuto. 



Hab. North Alabama. Prof. Tuomey. 



Lithasia Tuomeyi. Testa, tubereulata, valde inflata, subcrassa, tenebroso- 

 cornea ; spira obtuso conoidea. ; suturis impressis; anfractibus quinis, ultimo 

 grandi, infra suturis oblique tuberculatis ; apertura magna, rhomboidea, intus 

 albida, obsolete vittata, ad basira eanaliculata ; columella valde incurvata, su- 

 perne et inferne incrassata; labro expanso, margine acuto. 



Hab. North Alabama. Prof. M, Tuomey. 



Lithasia subglobosa. Testa, tubereulata, subglobosa, crassd, luteo-cornea, 

 bivittata; spira vix exerta; suturis impressis ; anfractibus quinis, ultimo gian- 

 dissimo, apud humeris tuberculatis ; apertura magna, rhomboidea, intus alba, 

 bivittata, ad basim eanaliculata; columella valde incurvata, superue et inferne 

 valde incrassata ; labro expanso, margine acuto. 



Hab. Tennessee. Prof. G. Troost. 



Lithasia dilatata. Testa laevi, subglobosa, subcrassa, glauco-virente, in- 

 fra suturis luteola, obsolete vittata ; spira obtuse conoidea; suturis irregulari- 

 ter impressis ; anfractibus quinis, ul'imo magno et ventricoso ; apertura grandi, 

 subrhomboidea, intus fuscescente, ad busim angulata; columella inferne et su- 

 perne incrassata, incurva; labro acuto et valde dilatata. 



Hab. Tennessee. Prof. G. Troost. 



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



BY ISAAC LEA. 



Neritina Showalterii. Testa, lasvi, rotundata, diaphana, luteo-cornea; 

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

 apertura semirotunda ; labio dilatato, albo, incrassato, edentulo et incurvato ; 

 labro dilatato, tenui, margine acuto. 



Operculum . 



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

 E. 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 aud 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. 



1861.] 



