MOLIiUSCA. 
In some, the lip of the margin is denticulated externally near the 
eniargination* * * § . 
In others it is entiref. The 
IVIoKio, Montf . — C'assidaria, Lam. 
Was separated from Cassis by Montfort. The canal curves less 
suddenly, and the whole shell leads directly to certain Murices. The 
animal resembles that of a Buccinum, but its foot is more developed 
Tekabra, Brug., 
The aperture, emargination and columella of a true Buccinum; but 
the general form is turriculated, that is to say, the spire is lengthened 
into a point §, In the 
Cerithium, Brug., 
Very properly separated from the Murex of Linnccus, we observe 
a shell with a turriculated spire ; the aperture is oval, and the canal 
short, but well marked, and reflected to the left or backwards. The 
animal has a veil on its head, and is furnished with two separated 
tentacula, on the side of which are the eyes, and with a round, horny 
operculum. 
Many are found fossil ||. M. Brongniart separates from the Ceri- 
thia the 
PoTAMiDA, Brongn. 
Which, with the same form of shell, has a very short and scarcely 
emarginated canal, no sulcus on the upper part of the right margin, 
and the external lip dilated. The Potamidae inhabit rivers, or, at least, 
their mouths, and fossil specimens are found in strata, which contain 
other fresh-water or land species only^. The genus 
* Buccinum vibex, Martini, II, x.\xv, .364, 365 ; — B. glaucum, List., 996, 60; — 
B. erinaceous, List., 1015, 73. 
-f- The Buccinum of the second division of Gmelin, except the B. echinophoruin, 
strigosum, No. 26, and tyrrhenum, which are Cassidariae. It must also he recollected, 
that, among the true Cassides, Gmelin appears to have several repetitions. 
J Buccinum caudatum, L., List., 940, 36; — B. echinipnnrum, List., 1003, 68; — 
B. strigosum, Gm., No. 26, List., 1011, 71, f. ; — Bucc. tyrrhenum, Bonam., Ill, 160. 
§ The whole of the last subdivision of the Buccina, Gmelin, such as, Buccinum 
maculatum, Li., 846, 74; — Bucc. crenulatum, L. List., 846, 75; — Bucc. dimidiatum, 
L., List., 843, 71; — Bucc. suhulatum, L., List., 842, 70, &c. 
M. de Blainville separates from them the genus subula, which he founds on a 
difference in the animal, and moreover on the presence of an operculum. 
II Murex vertagus, List., 1020, 83; — M. aluco. List., 1025, 87; — M. annularis, 
Martini, IV, clvii, 1486; — M. singulatus, Ib., 1492; — M. Terebella, Id., civ, 1458, 
9; — M. fuscatus, Gualt., 56, H; — M. granulatus. Martini, IV, clvii, 1483; — M. 
moluccanus, Ib., 1484, S. &c., with the numerous fossil species described by M. de 
Lamarck, Ann. du Mus. M. Deshayes has separated from the Cerithia, under the 
name of Nevinea, some small species, where the margin is prolonged into the aper- 
ture, and divides it into three distinct orifices. 
It is also near the Cerithia that w^e must place several fossil shells, which form 
the genus Nerinea of M. Defrance, and which is distinguished by strongly marked 
plicse on each whorl and on the columella, the centre of which, besides, is hollow 
throughout. Nine species are already ascertained. 
^ See Brongn., Ann. du Mus., XV, 367- In this subgemxs should be placed the 
CmYlimni Brug., List., pi. 115, f. 10; — Cer. palustre, f. Ib., 8.e6, f. 62; — 
C. muricatum, Ib., 121, f. 1 7, &c., and among the fossils, the Po/c»itda Z/cmar/r«, 
Brongn., loc. cit. pi. sxii, f. 3. 
