OP CONCIIOLOOY. 243 



Patulin^e. Shell moderately thick, translucent to opaque, 

 epidermis opaquely colored, sometimes banded or striped in 

 the large species, striate or ribbed, discoidal, planospiral, or 

 spire a little globosely elevated. Umbilicus wide. Mouth 

 not toothed, (lnmellately toothed in one species only. 



Linyual dentition. — Cncini bidentate, laterals either long or 

 square, bidentate or tridentate. 



VITRININiE. 



Genera. 



1. Vitrina, Drap. Shell very thin, polished, transparent, 



small, consisting of two or three depressed whorls, ra- 

 pidly increasing. Aperture very large, oblique, lunate. 

 Columellar margin a little inflated. Axis imperforate. 

 Nearly covering the contracted animal. 



2. Binneya, Cooper. Shell ear-shaped, nearly flat, whorls 



two, last whorl enormously expanded. One third as 

 long as the animal, which it does not half cover when 

 contracted. 



Much more depressed, with a larger proportionate aperture 

 than Vitrina. 



VITRINA, Drap. 

 1. Vitrina limpida, Gould. 



Plate 3, figure 1. 

 Globosely depressed, whorls 2|, scarcely convex, suture 

 very slightly canaliculate ; plane of aperture very oblique. Co- 

 lorless. 



Diam. 6 mill. 



Maine to Michigan, and Northward. 



2. Vitrina Angelica, Beck. 



Plate 3, figure 2. 



Globosely depressed, whorls 3|, suture crenulated, spire 

 small, somewhat prominent; aperture lunately oval, oblique. 

 Color greenish yellow. 



Diam. 6, height, 3*5 mill. 



Greenland. 



Mo^ globose, with one more whorl and more prominent 

 epire than No. 1. 



