CONGCHOLOGIA CEST RICA: 43 
Sub-genus PSEUDOHYALINA, Morse, 1864. 
Shell minute, discoidal, slightly convex above, uni- 
colored; closely striate, or ribbed; umbilicus large. 
P. minuscula, BINNEY. 
Helix minuscula, Binn., Boston Jour. Nat. P- neal 
2. & : 
Hists, (Eon 40. 
Shell slightly convex, whitish ; whorls 4, 
increasing slowly in diameter ; suture deep; 
umbilicus large; aperture rounded, spread- 
ing; lip thin, acute; columella with a thin 
callus; lingual membrane with 52 rows of 12-I-12 
teeth, each; buccal plate slightly arcuate, long, and 
narrow; anterior surface with faint jaw of P, minuseula. 
central, longitudinal striz, slightly Seat 
raised, on the centre of the cutting aig 

edge. H. 1, W. 2-2%, mill. 
Lingual Dentition of P. minuscula. — (Morse. ] 
Fig. 65, 

Station, in grass-fields, under sticks and stones. New 
Garden, Chester County ; not common. 
Sub-genus VALLONIA, Risso, 1826. 
Shell umbilicate, depressed; whorls 3'%4-4; aperture 
oblique, semicircular; peristome white; lip reflected, 
the margins approximate. 
