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I have examined V . vespertilio, V. nivosa, a n d V. u ndata.
The cavity o f the nuc leus in a cu t specimen o f V. vespertilio is nearly entirely filled with a n amber-
coloured pellucid calcareous d ep o s it; and th e whole o f the rest o f the cavity is lined with a thick glossy
deposit. The nucleus o f the shell is very thin, pale yellow, nearly transparent, with two indistinc t plaits on
its pilla r.
In a c u t specimen o f V . Hebreea (the nucleus o f which is destroyed) the cavity o f the u p p e r whorl is quite
filled w ith a white glossy deposit, and a similar d eposit lines the whole o f the inne r cavity o f the shells.
V o l u t a n i v o s a .— L a w .
The foot and head p u rp le with u nequa l white-edged black spots ; foot large.
V o l u t a u n d a t a .— L a w .
Fo o t pa le , with ne tted waved red brown lin e s ; head cross lined with red ; eyes rather far behind the
tentacles.
C O N O H E L IX .
The shells of this genus h ave no operculum.
They have the same nauseous odorous p u rp le secretion as the mitres.
I have examined the animal of Conohelix marmorata, C. olivceformis, a n d C. olivaria.
M ITR A .
The tru n k o f the mitres is v ery long, larger th an the shell ; their animals expand themselves very little.
The shells are extremely solid and d ifficult to break.
This genus from the inrmense numbe r o f species which it contains requires be ing divided into sections.
After considerable s tudy o f the species in their various stages of g row th ; the innumerable forms which they
exhibit agreeing with the different circumstances in which they live, I have be en induced to divide them t h u s:—
The th ro a t smooth, the oute r lip simple o r c ren u la ted ; they have four or five plaits in the p illa r. These
are the true M itre s. Some are variously dotted, as M . p apalis and M . episcopalis; others are smooth, like
Olives, as M .fis su ra ta , M . filosa. I 'h e rest have short spires and many plaits on the pillar—these form the
genus Conohelix of Swainson. Others with smoolh throats have the outer lip thickened internally, so as to
give them much the appearance o f Columbella, these form a good section.
M . bifasciata, M . retusa, §-c. with the M . Ziervogeliana and some allied species form another group
which is allied to this, b u t differing in having the inner lip thickened and expanded, and the outer lip toothed
internally.
The re st o f the M itr e s form a very good group for which the name Vulpécula may be retained, which
are peculiar for the ir throat being deeply grooved in all the stages o f the ir growth. The shells o f this section
are perfect P ro te i, 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 M itr e except in the length of the spire. The recent species Lamarck has referred to it
are Margine lla.
M i t r a r e t u s a . t . 36. / . 5.—Law. H i s t . vii. 319. Var.
The pilla r as seen in a section o f the shell is very thin and to rtu o u s; the plaits as the shell enlarges
become placed on th e back o f the canal of the former whorl, and the whole cavity of the u p p e r and the back
angle of the cavity o f a fevv o f th e succeeding whorls are filled with a clear glossy deposit. The inner parts
o f the whorls are so thin tha t the colour o f the last whorl is to be seen dislinclly through it.
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