CONCHOLOGIA CESTRICA. 



35 



A. alternata, SAY. 



Helix alternata, Say, Nich. Encyc., Amcr. Ed., 1816. 



A. alternata. [B. & B.] 

 Fig, 36, 



[Morse. J 



rig, 37, 



Shell orbiculate-depressed, obliquely, and closely, 

 ribbed-striate ; whorls 6, varied jaw of A. alternata. 

 with oblique, rufous bars, and 

 spots ; convex beneath, often an- 

 gular at the periphery ; aperture 

 oblique ; umbilicus large ; base ^^ ^^ ^ 

 paler, and less striate ; lingual membrane, with 1 21 

 waving rows, of 34-1-34, teeth, each ; buccal plate stout, 



Jjingual Dentition of A. alternata. [Morse.] 



rig, 38, 



of uniform width, and deeply striate, longitudinally, and 

 transverse. H. 8-10, W. 20-25, mill. 



Station, under wet logs, and boards, along streams. 

 Chester County ; common. 



