CONCHOLOGIA CESTRICA. 31 
T. appressa, Say. ae 
Helix appressa, Say, Jour. Phil. Acad. [B&B 
Peos, Lie re2e, 
Shell much depressed, pale yellowish; 
whorls 5, often sub-angulated, with fine 
transverse striz; aperture contracted; the 
white, reflected, lip, close appressed at 
base, and covering the umbilicus; the 
inner margin of the lip, mostly with one or two teeth; 
an oblique, compressed, white, tooth onthe | asd 
pillar lip; lingual membrane with 105 rows, eT 
of 40-1-40 teeth, each; buccal plate strongly Fig, 26, 
arcuate, the ribs, on the anterior surface, 
denticulating both margins. H. 7, W. 17, 
mill. 


Lingual Dentition of T. appressa. —[B. & B.] 
Fig. 27, 
FC a 
Station, under flat stones. On the Lehigh River, 
Pennsylvania. 
T. tridentata, Say. 
Helix tridentata, Say, Nich. Encyc., Amer. Ed., 1817. 
Shell very much depressed, light horn color, to 
chestnut; whorls 5, obliquely acute-striate; 7, tridentata. 
[B. & B.] 
Fig, 28 
aperture trilobate, contracted by a groove 
behind the lip; lip reflected, white, with _ 
two acute, projecting, teeth, on its inner @ 
edge; pillar lip with a strong, oblique, 
tooth in the aperture; strie converging 
into the deep, open, umbilicus. H. 8, W. 
15, mill.; very variable. 
Station, in fields bordering woods. Ches- 
ter County. | 


