248 CLASS III. GASTEROPODA. ORDER VII. PECTINIBRANCHIATA. 
Pl. CCLXXVI. Fig. 2. 
VoLvaARIA CONCINNA, Sowerby, Genera of Shells, No. 5. 
Pl. CCLXXVI. Fig. 3. 
Votvaria AcutTruscuLa, Sowerby, Genera of Shells, No. 5. 
MARGINELLA, Lamarck. 
Testa polita, ovato-oblonga, basi emarginata; spira brevi, nonnunquam 
depressa, pené occulta; apertura oblonga, interdum teste longitu- 
dinem zquante ; columella subzqualiter plicata ; labro externo mar- 
ginato, crassatim revoluto. 
The Marginelle were separated from the Linnzan Volute by Lamarck, 
on account of the outer lip of their shells forming a solid marginal varix 
on arriving at maturity, their spire being depressed in such a manner that 
the aperture nearly equals the length of the entire shell, and their uni- 
formly smaller size. And it is almost a matter of surprise that so 
marked an assemblage of good distinguishing peculiarities should have 
escaped the attention of Bruguiére, who may be safely styled the first 
reformer of the Linnzan school. The Marginelle are moreover the only 
mollusks of this family whose shells exhibit a bright enamel coating, like 
those of the Cypree and Olive, owing to their being entirely enveloped 
by the mantle. Adanson, indeed, confounded the Olive and Marginelle 
together for this reason in one and the same genus, under the title of 
‘Les Porcelaines”*; but that term was adopted by French writers in 
reference only to the Cypree. There are a number of species in this 
* It is true that the soft parts of the Olive and Cypree are not unlike those of the Mar- 
ginelle; a comparison of their anatomical peculiarities will. indeed, scarcely warrant the sepa- 
ration of these three genera in three different families; the shells, however, exhibit charac- 
ters really distinct from each other, and are, therefore, without any equivalent variation in 
their animal inhabitants. 
In descending to species, we find many variations admitted to be of specific importance in 
