36 CONCHOLOGIA CESTRICA. 
Sub-genus MACROCYCLIS, Beck, 1837. 
Animal of Macrocyclis concava,—([B. & B.) 
Fig 39. 

Shell moderate, thin, wide, umbilicate, depressed, 
striate, unicolored; whorls 4—5, the last wide, depressed, 
and deflected; aperture oblique, ovate; peristome slightly 
thickened, and reflected at base. 
M. concava, SAY. 
Helix coneava, Say, Jour, Pils Acady i. s.. Li te2t 
a Shell convex-discoid, pale horn color, 
|B. & Bb. 
sometimes with a tinge of green; whorls 
5, substriate, the last one flattened near 
the mouth, rounded, beneath; umbilicus 
wide, and deep; lip sub-reflexed, at base, 
and its extremities united by a columellar 
deposit ; lingual membrane with — rows, 
of 23-1-23,. teeth, cach; buceal plate 

crescentic, anterior surface striated, con- 
cave margin, with a slight projection. H.7, W. 16, mill. 
Lingual Dentition of M. concava. —[B. & B.| 
Fig. 42, 
Jaw of M.concava. 
[B. & B.] 
Fig, 41, 

Station, under stones, logs, etc. Chester County; 
not common. 
