FAMILY 10. PURPURIFERA. 239 
mella levi, subarcuata; labro externo simplici, acuto. Operculum 
corneum, parvum. 
The word Eburna (from ebur, ebony or ivory,) was selected for this 
genus by Lamarck on account of the very high natural polish of one of 
the shells which he referred to it ; one that was, however, referred to it 
from no other cause than the presence of an umbilicus, a character 
rarely to be relied on. This shell, his Eburna glabrata, has been the 
cause of no little confusion amongst conchologists ; for instead of pre- 
senting the same characters as the rest of the Eburne, it exhibits pre- 
cisely those of the Ancillari@, and a notion thence arose amongst authors 
that the latter ought to be regarded as the Eburne, whilst the species 
commonly retained under that title should either be distinguished by a 
new name, or carried back to their original place amongst the Buccina. 
Eburna is undoubtedly an inappropriate name for the shells under con- 
sideration, for they are generally coated with a thick epidermis ; whilst 
for the Ancillarie, on the contrary, no appellation could be better ; cus- 
tom, however, sanctions the application of it, and we cannot, therefore, 
do better than observe the arrangement which has been adopted by 
Sowerby in his ‘ Species Conchyliorum,’ in imitation of Swainson. The 
Eburna glabrata of Lamarck is there included with the Ancillarie, leaving 
the rest of his Eburnz undisturbed. The operculum is small, horny, 
and slightly hooked. 
Examples. 
Pl. CCLXXI. Fig. 1. 
Esurna Japonica*, Nobis, Proceedings Zool. Soc., 1842. 
Pl. CCLXXI. Fig. 2. 
EBURNA PAPILLARIS, Sowerby, Appendix to Tankerville Catalogue, p. 22. 
Conchological Illustrations, f. 9. 
* Cabinet of H. Cuming, Esq.: found on the sands at Japan by Dr. Siebald. 
Pht 
