EBURNA. 



TESTA ovata vel elongata, nitida, anfractuum 

 sutura occultata. Aperiura longitudinalis, 

 basi emarginata, labio externo simplicissimo, 

 basi unidentato. Columella superne umbili-^. 

 cata, infra umbilicum canaliculata. 



The differences between those shells to which Lamarck 

 first applied the name of Ehurna, and those which by the 

 general agreement of Conchologists have been appended 

 to them as belonging to that Genus^ are so great^ that we 

 cannot against our conviction, approve of their remain- 

 ing united ; wherefore our Ehurna, if it can with pro- 

 priety be considered as distinct from Ancilla, must consist 

 of the Bucciyium glahratum, Linn. Ehurna glahrata, Lam. 

 and such others as agree in those characters, which we 

 are of opinion circumscribe the Genus, and which are 

 commonly called " Ivoires'' in French, whence Lamarck 

 named the Genus Ehurna, It will be seen that Lamarck 

 has himself united the shells of which we speak all toge- 

 ther, continuing to regard the E. giabrata as the type of 

 the Genus ; but Swainson, thinking that those species 

 which least resemble E, giabrata, represent the characters 

 of the Genus in their perfect developements, has selected 

 one of them as the type of the Genus ; we hope, however, 

 to show that they do not even belong to it : but we will 

 first point out the characters of Eburna, and the marks 

 by which it is to be distinguished from Ancilla, to which 

 it is so nearly allied, that we should have hesitated to 

 separate the two genera, if both had not been decisively 

 adopted by authors. 



In general form the EhurncB are oblong, or even 

 yather elongated, shining or polished on the outside, and 



