EBURNA. 



having the suture of the volutions hidden hy the deposi- 

 tion of testaceous matter from the mantle^ which is di- 

 vided and spreads all over the shell when the animal is in 

 motion. Spire about half the length of the shell. Aper- 

 ture longitudinal^ its outer edge very even/ generally 

 having a very small point at its lower extremity^ and 

 deeply notched at its base. In all the above characters, 

 Eburna and Ancilla accord very nearly, while it will be 

 obvious that they are both separated by them from Buc- 

 cinum spiratum, and its cognate species ; but in Ehurna, 

 the Columella is umbilicate at its upper extremity, by the 

 separation of the inner lip from the lower part of the last 

 volution, and the lower part of the umbilicus forms a 

 double groove which runs round the outside of the twisted 

 Columella; in this consists the difference between Ancilla 

 and Eburna, the former having no umbilical suture : but 

 here we must observe, that of the known species of 

 Eburna, one has it much smaller than the rest, and 

 thus constitutes such a transition from the one Genus 

 to the other, as almost to confirm our doubts, as to the 

 propriety of separating them. The marks, by which 

 Eburna is to be distinguished from the other shells that 

 have been associated with it by Lamarck and others are, 

 the shells not being naturally polished on the outside, 

 their being covered with an epidermis, the volutions in 

 most species being separated by a canal, and the umbilicus 

 when it exists, being at the lower part of the Columella : 

 they have also an internal channel at the upper angle of 

 the aperture ; first noticed by Swainson. 



The true Eburna should be placed next to Ancilla, 

 and not where Lamarck has arranged them, among the 

 Purpuriferes ; they have no operculum, and are marine : 

 three or four species only are at present known one alone 

 is described : we have represented at 



Fig. 1 & 2. Eburna glabrata. Lam. Buccinmn glabratum, Linn. 



3. &4. — balteata, Nob. Testa cylindraceo-oblonga, spir^ sub- 

 conic^, anfractu ultimo supern^ incrassato ; infern^ balteato. 



Obs, — A little shell diff'ering in form, and in the di- 

 mensions of its umbilical suture from E. glabrata; we 

 are unacquainted with its locality. 



