NATURAL SCIENCES OF PHILADELPHIA. 397 



Melania V i r g i n i c a, 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 carina?, 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. 



Indent 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. car in at a, De Kay. Very abundant. The carina is prominent and 

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

 revolving brown bands. 



x a 



Rissoina;. 

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



VlVIPARIDiE. 



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

 pressed spiral lines. 



Valvatidje. 



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. 



HELICIDiE. 



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 

 its base numbers of dead shells, which are found in all stages of preservation. 

 In some places, where well protected, these shells actually lay in heaps. In a 

 decayed log by the water side, nearly one hundred specimens of Helix and 

 Pupa were obtained. A close search on the hills on the north side of the Po- 

 tomac failed to discover a single species of Helix or Pupa. 



Helix albolabris, Say. Diameter 1-25 inch. Spire rather depressed, 

 and aperture sub-triangular. Reflected lip very broad and flat, with a ten- 

 dency to form a tooth-like lamina near the umbilical region. Striae coarse 

 and crowded. 



H. thyroides, Say. A few specimens obtained. 



H. monodou, Rackett. This species appears to be rare at Harper's Ferry. 

 I found but one individual. 



H. hirsuta, Say. Common. All that were collected are entirely desti- 

 tute of the hairy epidermis. There is considerable difference in the convexity 

 of the upper surface, the spire being sometimes rather depressed. 



H. concava, Say. Dr. Binney, in his "Terrestrial Mollusks," states 

 that the upper and lower extremities of the lip are united in this species by a 

 thin callus on the columella. In the single specimen found by me, the callus 

 is very prominent. 



H. profu nd a, Say. Numerous. Attaining quite a large size, and with 

 close, narrow, raised striae. But one brown revolving band is visible. 



H. pulchella, Mailer. Rare. 

 1861.] 



