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MOLLUSCOUS ANIMALS. 
I have examined V. vespertilio, V. nivosa, and V. undata. 
The cavity of the nucleus in a cut specimen of V. vespertilio is nearly entirely filled with an amber- 
coloured pellucid calcareous deposit ; and the whole of the rest of the cavity is lined with a thick glossy 
deposit. The nucleus of the shell is very thin, pale yellow, nearly transparent, with two indistinct plaits on 
its pillar. 
In a cut specimen of V. Hebrcea (the nucleus of which is destroyed) the cavity of the upper whorl is quite 
filled with a white glossy deposit, and a similar deposit lines the whole of the inner cavity of the shells. 
Voluta NIVOSA. — Lam. 
The foot and head purple with unequal white-edged black spots ; foot large. 
Voluta undata. — Lam. 
Foot pale, with netted waved red brown lines; head cross lined with red; eyes rather far behind the 
tentacles. 
CONOHELIX. 
The shells of this genus have no operculum. 
They have the same nauseous odorous purple secretion as the mitres. 
I have examined the animal of Conolielix marmorata, C. olivceformis, and C. olivaria. 
MITRA. 
The trunk of the mitres is very long, larger than the shell ; their animals expand themselves very little. 
The shells are extremely solid and difficult to break. 
This genus from the immense number of species which it contains requires being divided into sections. 
After considerable study of the species in their various stages of growth ; the innumerable forms which they 
exhibit agreeing with the different circumstances in which they live, I have been induced to divide them thus : — 
The throat smooth, the outer lip simple or crenulated ; they have four or five plaits in the pillar. These 
are the true Mitres. Some are variously dotted, as M. papalis and M. episcopalis ; others are smooth, like 
Olives, as M.fissurata, M. filosa. The rest have short spires and many plaits on the pillar — these form the 
genus Conolielix of Swainson. Others with smooth throats haye the outer lip thickened internally, so as to 
give them much the appearance of Columbellce, these form a good section. 
M. bifasciata, M. retusa, Spc. with the M. Ziervogeliana and some allied species form another group 
which is allied to this, but differing in having the inner lip thickened and expanded, and the outer lip toothed 
internally. 
The rest of the Mitres form a very good group for which the name Vulpecula may be retained, which 
are peculiar for their throat being deeply grooved in all the stages of their growth. The shells of this section 
are perfect Protei, the species assuming in different situations such very different colour and forms. 
The genus Volvaria of Lamarck, restricted to the fossil species for which it was established, does not 
differ from the true Mitre except in the length of the spire. The recent species Lamarck has referred to it 
are Marginella. 
Mitra retusa. t. 36. /. 5. — Lam. Hist. vii. 319. Var. 
The pillar as seen in a section of the shell is very thin and tortuous ; the plaits as the shell enlarges 
become placed on the back of the canal of the former whorl, and the whole cavity of the upper and the back 
angle of the cavity of a few of the succeeding whorls are filled with a clear glossy deposit. The inner parts 
of the whorls are so thin that the colour of the last whorl is to be seen distinctly through it. 
