CONCHOLOGIA CESTRICA. 



Sub-genus MACROCYCLIS, BECK, 1837. 



Animal of Macrocyclis concava. [B. & B.] 



Fig 39, 



JIT. concava. 



[B. & B.J 



Pig, 40, 



Shell moderate, thin, wide, umbilicate, depressed, 

 striate, unicolored; whorls 45, the last wide, depressed, 

 and deflected; aperture oblique, ovate; peristome slightly 

 thickened, and reflected at base. 



M. concava, SAY. 



Helix concava, Say, Jour. Phil. Acad. F. S., II., 1821. 



Shell convex-discoid, pale horn color, 

 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, each; buccal plate 

 crescentic, anterior surface striated, con- 

 cave margin, with a slight projection. H. 7, W. 16, mill. 



Jjingual Dentition of M. concava. [B. & B.] 



Fig. 42. 



,TaivofM. concava. 



[B. & B.J 



Fig, 41, 



Station, under stones, logs, etc. Chester County; 

 not common. 



