307 Bulletin 5 37 



FOSSIL SHELLS. ^3^ 



and attached by one side, from its summit to its 

 edge, to the shorter side of the shell ; its summit 

 corresponding to the inner apex of the shell. 



This very remarkable shell is perfectly distinct 

 as a species from any other yet known. That it 

 does not, in rigid accuracy, belong to the genus 

 Calyptr^a, must be evident to every conchologist 

 who considers the characters laid down in the 

 above description, and who is, at the same time, 

 aware, that the internal appendage of the type of 

 the genus, is open on one side throughout the 

 whole of its length. If it be not properly a Ca- 

 LYPTR^A, it cannot be referred to the closely re- 

 lated genera lNFUNDiBULUM,Montf. and Mitrula of 

 Gray, much less to any other genus with which 

 we are acquainted. I therefore propose that it be 

 placed in a new genus under the following name 

 and characters. 



DISPOT^A. 



Shell univalve, conoidal, patelliform, with an 

 internal entire cup-shaped appendage, adhering 

 by its side and apex to the side of the shell. 



To this genus will also be referred a recent spe- 

 cies brought by I^ieut. Gantt, U. S. N. from South 

 America, and presented by him to the Academy. 

 Of this shell I cannot find any description, and will 

 therefore characterize it as follows : 



D. tubifera. Shell oval, inequilateral, with small 



[J. A. N. S., Phila., ist Ser., Vol. IV, 1824.] 



