CONCHOLOGIA CESTRICA. 



H. electrina. 



[B. & B.] 

 Fig, 60, 



Station, under logs and loose bark. Chester County ; 

 frequent. 



H. electrina, GOULD. 



Helix electrina, Gould, Invert, Mass., 1841. 



Shell very thin, pale; whorls 3^, the 

 last rapidly enlarging ; spire depressed ; 

 aperture rounded ; peristome simple, acute ; 

 lip not flexuous; umbilicus very narrow, 

 and deep. H. 2, W. 4, mill. 



Station, in company with the preceding. 

 Chester County ; rare. 



H. arborea, SAY. 



Helix arboreus, Say, Nich. Encyc., Amer. Ed., 1817. 



Shell much depressed, thin, shining, amber- 

 colored; whorls 4^, increasing regularly; 

 umbilicus moderate, deep ; lip slightly flexu- 

 ous ; lines of growth indistinct. H. 2^, W. 

 5, mill. 



Station, under decayed wood, and rubbish. 

 Chester County ; abundant 



H. hydrophila, INGALLS. 



Helix hydrophiia, Ingalls, in collection unpublished. 



Shell depressed-conical, thin, amber- 

 colored ; whorls 4 to 4 J^ ; suture well 

 impressed; umbilicus deep, crateriform; 

 aperture lunate, sub-deflected; lip thin, 

 sub-angular. H. 3, W. 6, mill. 



Station, under logs, and boards, near 

 the water. Schuylkill tide marsh, Phila- 

 delphia. 



OBS. We prefer to keep this distinct from H. nitida, 

 Mull., of Europe. 



H. arborea. 



[B. & B.] 

 Fig, 61, 



