CONCHOLOGIA CESTRICA. 
Oo 
‘oa 
A. alternata, Say. 
Helix alternata, Say, Nich. Encyc., Amer. Ed., 1816. 
A, alternata. —[B. & B.] 
Fig. 36. 

Shell orbiculate-depressed, obliquely, and closely, 
ribbed-striate; whorls 6, varied ~ ‘jaw of A. alternata. 
: G E a BA m {[ Morse. | 
with oblique, rufous bars, and Fig. 37, 
spots; convex beneath, often an- 
gular at the periphery; aperture 

oblique; umbilicus large; base 
paler, and less striate; lingual membrane, with 121 
waving rows, of 34-1-34, teeth, each; buccal plate stout, 
Lingual Dentition of A. alternata, — ! Morse. ]} 
Fig, 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. 
