OP CONCHOLOGY. 247 



2. Perforate or umbilicate. 



* Very globose. 



2. Hyalina friabilis, fm. G. Binney. 



Plate 3, fig. 12. 



Whorls 5, rapidly increasing; shell very globose, thin, pol- 

 ished, faintly striate, suture scarcely impressed ; aperture sub- 

 circular, sharp lipped, very slightly thickened at base, and a 

 little reflected over the narrow, deep umbilicus; shell very 

 convex below. Color light horn to reddish. 



Diameter 20 to 25, alt. 12 to 15 mill. 



South Indiana and Illinois, Arkansas, Alabama, Texas. 



** Globosely depressed. 



(Subgenus Omphalixa, Rafinesque, W. Gr. Binney.) 



f Closely striate above, smooth beneath. 



Diam. = 20 mill. 



3. Hyalina laevigata, Pfeiffer. 



Plate 3, fig. 13. 



Whorls 5, yellowish or fulvous, very closely and regularly 

 striate above, smooth and shining beneath ; last whorl ex- 

 panding towards the aperture, which is rounded lunular ; lip 

 simple, slightly reflected around the moderate umbilicus, and 

 much thickened within at base. 



Diam. 20 mill. 



Ohio, Indiana, and southwards to Florida, Mississippi and 

 Arkansas. 



,ft Smooth, or coarsely, irregularly striate. 

 Diam. = 25 — 35 mill. 



4. Hyalina lucubrata, Say. 



Plate 3, figure 14. 



Depressed, sub-globose ; whorls more than 4, much wrin- 

 kled, sub-translucent, reddish-brown, polished, beneath paler; 

 umbilicus rather large ; aperture nearly orbicular. 



Diam. 26, height 12 mill. 



Mexico. 



Differs in color and in being more depressed and more coarse- 

 ly striate, from Isevigaia, Pfr. 



