From Proceedings of t ho Academy of Natural Scionees of Philadelphia, Dee. 18G1 



On the Mollusca of Harper's Ferry, Virginia. 



BY GEORGE W. TRYON, JR. 



In the month of June, 1S59, I was called by business to Harper's Ferry, and 

 while there, having a very brief period of leisure at my disposal, I employed 

 it in making a collection of the shells of the vicinity. I was struck at the 

 time with the exceeding abundance of these, both in individuals and species, 

 and also by the prevalence of certain external characters, much more promi- 

 nently marked, than in the same shells from the vicinity of Philadelphia. 

 These peculiarities, on a recent re-inspeetion of the shells, have appeared to 

 me worthy of mention ; and the subject of geographical distribution may re- 

 ceive some new light from the publication of a list of the Mollusca of the 

 mountainous region of Virginia. The species collected are as follows : 



GASTEROPODA. 



Melaniad^e. 



These shells were numerous upon the rocks in the bed of the Potomac, just 

 below the junction of the Shenandoah River, and at the TJ. S. Rifle Armory 

 on the latter stream. 



Melania Virginica, Gmelin, sp. — The whorls well rounded, and entire to 

 the apex. Frequently smooth, but the carinated varieties more abundant ; 

 (M. multilineata Say) ; on these, the carinse, varying from three or four to 

 eighteen on the body whorl, are raised and sharp, and on the more crowded 

 ones, the interstices are densely striated by the longitudinal lines of growth. 

 All the specimens are distinctly banded with brown. Length reaching 1-5 

 inches. 



Leptoxis i s o g o n a, Say. Three specimens found. 



L. dent at a, Couthouy. Very numerous. Epidermis generally a rather 

 brilliant green. Transverse brown bands, two near the base, and one near the 

 suture. 



L. nigrescens, Conrad. Numerous. Inhabiting with L. dentata. 



L. carinata, De Kay. Very abundant. The carina is prominent and 

 sharp, giving the shell a trochiform appearance. Color light horn, with faint 

 revolving brown bands. 



RlSSOIDJE. 



Amnicola 1 i m o s a , Say. Exceedingly abundant. 



Viviparid^e. 



Vivipara d e c i s a , Say. Rare. Epidermis distinctly striate, with im • 

 pressed spiral lines. 



Valvatice. 



Valvata tricarinata, Say. Very numerous, but not so much so as the 

 variety bicarinata, Lea. A few specimens of the smooth variety simplex were 

 gathered. None of the individuals collected had attained more than one- 

 eighth inch diameter. 



Helicid^. 



The towering wooded hills on the south side of the Potomac and Shenan- 

 doah, are thickly inhabited by Pulmonates. Every projecting rock which 

 arrests the downward course of the mountain torrents, has gathered around 



