1818.) GENUS POLYGYRA. 279 



<:ave beneath; beneath, the four exterior volutions equally 

 prominent, transverse diameters equal to those of the up- 

 per surface; umbilicus central, moderate, attenuated to 

 the apex so as to exhibit the remaining volutions. 



Breadth, Female two-iifths, 



Male three-tenths of an inch. 



Inhabits Georgia and East Florida. 

 Cabinet of the Academy. 



A very common shell in many parts of Georgia, pai'- 

 ticularly the sea-islands, also in East Florida. We found 

 them numerous under the ruins of old Fort Picolata on 

 the St. John's river, and on the Oystershell Hammocks, 

 near the sea, and in other situations, under decaying Pal- 

 metto logs, roots, &c. 



These shells would have been referred by Linne to 

 the genus Helix, but as that genus has been limited by 

 IVIr. Lamarck, and others, to those shells of which the 

 apertures are broader than long, I cannot, with propriety, 

 in the present state of conchology, consider them as of 

 that genus. Neither can I refer them to either of the ge- 

 nera which have been separated from Helix by Messrs. 

 Lamarck, Montfort, &c. by the characters which those 

 naturalists have given of their genera. They differ from 

 others in having the pillar lip elevated considerably above 

 the surface of the penultimate ^vhor^, so as to be equally 

 prominent with the outer lip, with which it foiTns an un- 

 interrupted continuation, and by the concavities beneath the 

 lips, formed by the protrusion of a portion of the shell into 

 the aperture. In this last character it approaches the ge- 

 nus Caprinus of Mr. Montfort, but differs in being um- 

 bilicated. 



