CONCHOLOGIA CESTRICA. 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- *in/a?uirt, 

 Hist., III., 1840. Pig. 63', 



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 12-1-12 

 teeth, each ; buccal plate slightly arcuate, long, and 

 narrow; anterior surface with faint j aw of P . minuscula . 

 central, longitudinal striae, slightly [Morse.] 



raised, on the centre of the cutting 

 edge. H. I, W. 2-2^, mill. 



lingual Dentition of P. minuscula. [Morse.J 

 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; aperture 

 oblique, semicircular; peristome white; lip reflected, 

 the margins approximate. 



