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Subgenus STRIATURA, Morse, 1864. 



Shell small, striate, thin, translucent, without teeth in the 

 aperture. 



Jaw almost smooth, with a median furrow and notch ; central 

 tooth of the radula very large. United States. 



Distinguished chiefty by the jaw and dentition. 



Section PSEUDOHYALINA, Morse, 1864. 



Shell minute, subdiscoidal, slightly convex above, unicolored, 

 closely striate-ribbed, umbilicus moderate. N. America. 



Chanomphalus, Strebel, 1880, is a synonym. 



Section PYCNOGYRA, Strebel, 1880. 



Shell many-whorled, depressed conical above, whorls narrow, 

 ribbed-striate, translucent ; umbilicus rather large, bordered by 

 an obtuse angle. Mexico. 



Subgenus JANULUS, Lowe, 1852. 



Shell umbi Heated, depressed orbicular, costulat^ly striate 

 above, rather smooth below ; whorl 7-8^, closely revolving, the 

 last convex at the base ; aperture lunar, peristome simple, thin, 

 with a callous ring within. Madeira. 



Jaw and radula typical. 



Genus SELKNITES, Fischer, 1879. 



Shell depressed orbicular, widely perspectively umbilicated, 

 strongly striate above, last whorl obliquely depressed above, 

 depression becoming more marked at the aperture ; extremities 

 of the-peristome approaching. 



Animal having the jaw of Zonitida?, but the dentition of the 

 Testacelli<la>. United States. 



On account of the jaw and dentition, Dr. Fischer has made 

 this group the type of a family Selenitidae, interposed between 

 Testacellida} (having similar teeth, but no jaw), and Zonitidae 

 (having similar jaw. but different teeth). 



Section HAPI.OTIIKMA, Ancey, 1881. 

 Shell much smaller, peristome sharp. 



Section MORCHIA, Albers, 1860. 



Shell darker colored, striatulate. West Indies. 



