GENUS DOLIUM. 3 
to the state in which Linneus had left them: he places them 
between Harpa and Buccinum. De Blainville has arranged 
them in his family Entomostomata, between Harpa and Casst- 
parta. This writer divides them into three sections: first, 
species having an ovate form, spire pretty prominent, right lip 
always thin, such as the Dotium perdix and rufum (I consider 
this last species only as a variety of the perdiz, or as an injured 
specimen); second, those with a short spire, more ovate and 
more globular, of which the galea and olearium, present exam- 
ples; third, the Cassis-formed tuns, always oval, more or less 
globular, with very distant ribs, the right lip bordered, and the 
. columella twisted at its extremity, such as the Dotium macula- 
tum, fasciatum, variegatum and pomum. 
Latreille, in his work, Familles Naturelles, &c., includes the 
Tuns, the Harps, and several other genera in a single family of 
his order Gasteropoda, to which he gives the name of Dolium- 
formed. I agree, in some respects, with the opinion of this 
writer, that the approximation which he makes of the Harps and 
the Tuns appears natural, and founded upon a very important 
character, that of the absence of the operculum in both genera. 
But, I think that they should form not one family, but a separate 
division, and therefore I shall class them among the Purpurifera, 
of which they should certainly make a part, on account of their 
affinity to all the other genera comprised in this family. I retain 
for my division the term Dolium-formed, because I separate from 
the family of the same name, the genera Monoceros, Concno- 
LEPAS, and Purpura, which I refer to the Buccinoidea of the 
same author. 
With regard to the divisions which De Blainville has establish- 
ed in the genus which I am examining, I think they are founded 
upon characters too variable and too superficial for me possibly 
to adopt. Ihave replaced them by the two groups of which I 
have spoken, and which I thus characterize : the first, with the 
right lip always thin, and undulated; the second, with the right 
lip more or less thickened by the margin, and pretty strongly 
denticulated. I have thought that a shell which Valenciennes 
had determined under the generic name of Matra, (Recueil 
d Observations de Zodlogie, Humb. et Bonpland, p. 325), ought 
