CONCHOLOGIA CESTRICA. 63 
R. columella, Say. 
Lymnea columella, Say, Jour. Acad. Phila. F. S., L, 
1817. 
. columella. — [W. G. B.] Jaw of R. columella.—[W. G. B.] 
Fig. 117. Fig. 118. 
EI 

Shell, thin, fragile, pale; whorls 4; spire acute; aper- 
ture expanded, ovate ; columella narrowed near the base, 
so as to exhibit the interior of the spire. H. 15, W. 8, 
mill. 
Lingual Dentition of R. columella. —([W. G. B.] 
Fig, 119, 
sony 
AG, 7 
Dog 
® 
*Soropapsbotil 
Station, stagnant streams and muddy pools. Chester 
County ; common. 
R. macrostoma, SAY. 
Lymneus macrostomus, Say, Jour. Acad. Phila. F. S., 
Mento 2h 
Shell, sub-oval, thin, and fragile, straw-yellow ; whorls 
5 with the lines of erowth “crossed Dy 9: macrostoma: 
[W. G. B.] 
Fig, 120. 
minute spiral stri2; suture impressed; 
spire acute, one-third the length of the 
aperture, which is large and expanded; 
outer peritreme slightly reflexed and 
forming (with a thin coat of calcareous 
matter on the columella) a slight umbili- 
eusi* Hh zor W: 12; mill. 
Station, ponds. Pickering Creek; Chester County. 

