346 MOLL 
Mollusca. of the reader. When speaking of the Conchyliologie Sys- 
—\—" fématique of that author, in reference to this subject, he 
USCA. 
Draparnaud, which he calls Paysa. They are all sinistral Mollusca, 
shells, and will require further division when the form of the ~=\—== — 
says, “ Ow presque toutes les especes et méme des variétés 
sont erigées en genres.” 
19. Conus.—This genus is so very natural, that it has 
undergone no changes since the days of Linnzeus, except by 
the addition of new species. That author was acquainted 
with thirty-five species and a few varieties; but M. Hawss 
communicated to Bruguiére descriptions of one hundred and 
forty-six, from specimens existing in his own cabinet. We 
cannot boast of any British species. 
20. Cypr#a.—This genus is equally natural as the for- 
mer. It has undergone no change since the days of Major. 
21. Butta.—This genus presents to the mere conchologist 
a source of great perplexity. It displaysat once the absurdity 
of dividing the molluscous animals into testaceous and naked, 
since no such distinctionis observable in nature. Many of 
the shells which were formerly included in this genus are 
found to be contained within the common integuments of 
the animal. It was this circumstance which induced Lin- 
nus to separate the limax and the aplysia from the vermes 
testacea. Both of these have shells, but they are concealed. 
In imitation of the same principle, Lamark has formed a new 
genus among the naked mollusca, called Buti», for the 
reception of those bulle in which the shell is concealed. 
The bulla aperta is the type of the genus. The bulla plu- 
mula of Montagu is another shell included in the animal, 
which is very closely connected with the genus Pleuro- 
branchia of Cuvier. (Annales du Mus. v. 269). It may be 
asked, are all the other bullz found in similar situations, and 
consequently do they belong to the naked mollusca? La- 
mark considers, and apparently with reason, that all those 
which are’distinctly spirally involuted, and ornamented with 
colours, are not entirely inclosed in the cloak of the animal, 
and ought therefore to be ranged with the testaceous mol- 
lusca. How few British species does this character include. 
As originally constituted, the genus of Linnzus contain- 
ed species of very different characters, so that many new 
genera have been formed. To Bruguiére, Lamark, and Dra- 
parnaud, we owe all the improvements which have taken 
place. 
The modern genus Buxxa includes those shells which cor- 
respond with the following character :—“ Testa univalvis, 
convoluta, ovato-gibbosa vel cylindracea: spira non exserta, 
apertura longitudine testa, labro acuto.”. The B. ampulla 
is the type of the genus. 
The genus Ovuta, instituted by Bruguicére, is more nearly 
related to the cyprea than to the bulla. It differs, however, 
from the former, in the left margin of the lip being smooth; 
and from the latter, in the edges of the mouth being rolled 
inwards, and in the shell being produced at both ends. The 
B. ovum of Linnezus is the type of the genus; the B. patula 
of Pennant. 
The bulla terebellum has been employed by Lamark to 
constitute his genus TrEREBELLUM. The canal at the base 
of the mouth, and the truncated pillar, furnish the generic 
characters. 
Linnzeus was for some time uncertain where to place those 
shells which he at last inserted in the genus bulla, under the 
trivial names ficus and rapa. These, with afew of the mu- 
réces of the same author, constitute the genus Pyruta of 
Lamark. Its canaliculated base removes it from the bulla, 
while the short spire, the swelling of the last whorl, the 
smooth pillar, and pyriform shape, distinguish it from all 
those with which it is apt to be confounded. It is more 
nearly allied to the Fusus than to any other. 
The preceding genera consist of species which live in the 
sea. The B. virginea is a terrestrial shell, and ought to 
form a distinct genus next the bulinius. The B. fontinalis, 
hypnorum, and rivalis, reside in fresh water. They have, 
with much propriety, been formed into a distinct genus by 
animal shall become the basis of generic distinction. The 
Jontinalis and hypnorum are natives of Britain. 
In the genus Acwattna of Lamark, the pillar is trun- 
cated_as in the terrebellum, but the base of the mouth is 
entire. Itis represented by the bulla achatina of Linnzus. 
To this genus we may refer the Buccinum acicula of Miiller, 
which is found in England, and the Helix octona of Lin- 
nzus, erroneously considered as a native of Britain. 
22. VotutTsa.—This genus, as originally formed by Lin- 
nzeus, depended, as he informs us, on the plicz of the pillar, 
“volutee genus facillime distinguitur columella plicata.” But 
as this character belongs to many shells otherwise very dif- 
ferent in form, succeeding conchologists have separated 
many species from the genus, and reduced it within more 
natural limits. As it now stands it is thus defined, “ Testa 
univalvis, ovata, subventricosa, apice papillari; basi emargi- 
nata. Columella plicata; plicis inferioribus, majoribus, vel 
longioribus.” The type of the genus is the voluta musica. 
Bruguiere removed from the Linneean genus those species 
which are destitute of a groove at the base of their mouth, 
and of which Lamark formed the genera AurtcuLa, Tor- 
NATELLA, and VotvarraA. In the latter the spire is not 
produced; in the former it is produced. To the genus au- 
ricula, which contains land-shells, the V. awris-mide and 
auris-jude belong. The V. tornatilis is the type of the 
genus tornatella. In his reference to the genus volvaria, 
Lamark quotes the bulla eylindracea of Pennant and Da 
Costa, as if they were one and the same. But Pennant’s 
shell is a true bulla, while that of Da Costa is regarded as 
the voluta pallida of Linnzeus, and probably belongs to this 
genus. 
In the genus Oxtva, the turns of the spire are separated 
externally by a very distinct gutter or canal, and the pillar 
is obliquely striated. The voluta oliva of Linnzeus contains 
many different species of this genus, which are remarkable 
for the smoothness of their surface and the brilliancy of their 
colours. 
The Ancrixa, which, like the former, is of a sub-cylin- 
dric form, is destitute of the groove which separates the 
whorls, and is characterised by an oblique callous ring at 
the base of the pillar. 
In the genus Mirra of Lamark, the spire is pointed in- 
stead of ending in a small knob, as in voluta, and the plicee 
of the pillar increase in size from the base upwards, which 
isthereverse in that genus. The V. episcopalis of Linnzeus is 
the type of this genus, which contains many species much 
sought after by collectors. 
In the CotumBetta, the shell is oval, the spire short, 
and the inner edge of the right lip is swollen. The /. 
mercatoria is the type of the genus. 
The MarctneExta is very distinctly marked by the pro- 
minent callous collar which surrounds the outside of the 
right edge of the shell. The opening of the mouth at the 
base is scarcely grooved. The V. glabeliais the type of the 
genus. 
The CancrLzanrta is nearly related to the genus colum- 
bella, but the absence of the swelling of the lip, and the 
presence of the compressed sharp plicee of the pillar, furnish 
sufficiently obvious characters of distinction. The V. can- 
cellata of Linnzeus is the type of the genus. 
In the genus Tursrvetuus the shell is turbinated, sub- 
fusiform, and canaliculated at the base, having from three 
to five transverse compressed plicz on the pillar. The V. 
pyrum is the type of the genus. 
23. Bucctnum.—This is another of the Linnzean genera 
of shells, which has undergone great alterations. As origi- 
nally constructed, it embraced many distinct groups of shells, 
which Bruguiére and Lamark have since formed into ge- 
nera. The restricted character of the genus Buccinum is 
