sent me the individual represented in the upper part of the 

 plate. It is seated on a Conopea elonsala, S. which is at- 

 tached to a branch of our common Gorgojna. He cbtain- 

 it at Sullivan's island. The tendency towards the de- 

 pressed spiral form in this shell, evinced by the great obli- 

 quity of the cardinal portion, which hardly protrudes be- 

 yond the margin, would arrange it with the genus Gry- 

 phaea in the estimation of some authors ; a group, how^ever, 

 which we consider as a mere subdivision of the present 

 genus. On the lower part of the plate is represented one 

 of many specimens which I obtained in Florida attached 

 to various objects. It seems to be closely related to a fos- 

 sil of Virginia, to which Mr. Conrad has given the name 

 of O. solea, but as m}^ specimen of that shell is imperfect 

 and 1 have not his description, 1 cannot determine the de- 

 gree of affinity ; it may possibly be a variety of that spe- 

 cies. I have also a specimen from the Antilles, and another 

 that is reversed o 



REFERENCE TO THE PLATE. 



The two upper figures ; natural size. .'Middle figures, interior of the :wo 

 ralvcs, magnified. 

 Loiver figure, a large specimen, exterior view. 

 PI. id. 



