Gasteropoda. MOLLUSCA. Proroscidieeka. 
i534 
power of retracting the float. In rough weather-, 
however, they are driven about by the agitated sea, 
and their floats are then broken or detached ; but even 
then the shells are found floating on the surface. In 
this state they are frequently drifted to our own shores, 
especially on the soutlrern and wester-n sides of the 
island ; and in Swansea bay, we are told, the animals 
have been found quite fresh. The favourite food of 
the lanthinge appears to be the gelatinous Velellw, 
and M. Deshayes informs us that he has often witnessed 
them feeding upon these animals, and apparently 
making use of them at the same time as a raft to float 
them on the surfaee. It has been said that in con- 
sequence of feeding upon these blue-coloured Acalephae 
the lanthinse obtain their violet hue. It is certain that 
they have the power of secreting a quantity of violet 
fluid, and that when molested they exude it in consider- 
able abundance. 
THE COMMON VIOLET SNAIL {lantMna communis), 
according to the late Professor Forbes, secretes this 
fluid rapidly, and the purple dye, he says, was so 
strong, that some paper which he painted with it in 
1837, retained its colour strongly in 1853. M. 
Lesson tried to prove that this was the very shell 
which Pliny described as the one from which the 
Tyrian dye was obtained. It occurs frequently in the 
Mediterranean ; but the colour of the fluid of this 
mollusk is purple on its emission, and is remarkably 
defective in permanency. The species of lanthina are 
not numerous, but some of them are diffused over a 
great part of the world, the shells being thrown up on 
the sea-coasts by gales of wind. At certain seasons 
the beaches of St. Helena and the island of Ascen- 
sion are entirely covered with them. Mr. A. Adams 
found them cast up by thousands on the shores of the 
Meiaco-shimah islands, but he says he never observed 
them make the slightest attempt to crawl, though he 
frequently noticed them adhering together in masses, 
attached by the anterior part of the foot, which acted 
as a sucker. 
Family — SCALARIIDHH {The Wentle-traps). 
The Wentle-traps are very different-looking shells 
from the Violet Snails, but the arrangement of the 
teeth in the animals is nearly the same. The shell 
is spiral, turreted, with varices, or elevated longi- 
tudinal ribs, on the whirls. The aperture is rounded, 
entire, and exhibits scarcely any trace of a canal. 
The operculum is horny, spiral, few-whirled. The 
species are numerous, about one hundred species 
being found recent, and an equal number having been 
described as inhabitants of our globe at an earlier 
period of its existence. 
The genus Scalakia, the “ Wentle-trap ” is the 
SUB-OKDER III.- 
The Rostriferous mollusca are equally numerous as 
the Proboscidiferous ; but instead of being carnivorous 
in their habits, they are essentially vegetable feeders. 
only one of the family, and the species are chiefly from 
the eastern tropical seas. China and the Philippine 
islands harbour the greater number, but five species are 
natives of the British isles. 
THE ROYAL STAIR-CASE or W'extle-TEAP, “la 
vraie Scalata” {Scalaria pretiosa), is the most remark- 
able and the most valuable of all. This shell, always 
distinguished for its beauly, and once famous for the 
enormous value set upon it bj' collectors, is a native of 
the Chinese seas. It grows to more than two inches 
in length, is conical, umbilicated, and twisted into a 
loose spire, so that the whirls only touch each other by 
their projecting ribs. It is of a pale yellowish coloui', 
with white ribs or varices. “ The specific name given 
to it by Lamarck” {pretiosa), says Mr. Broderip, “was 
at one time well deserved on account of its rarity, and 
the great price which a fine specimen would bring in 
the market, especially when it exceeded two inches in 
height ; such a specimen has been sold in former days 
for twenty-four hundred livres, or one hundred louis. 
But these times are gone by; the shell is no longer 
rare, and good specimens only fetch shillings where 
they once brought pounds. A very fine example still, 
however, commands a considerable sum. That in Mr. 
Bullock’s museum, supposed to be the largest known, 
brought £27 at his sale, and was in 1815 estimated at 
double that value.” Da Costa, in his “ Elements of 
Conchology,” informs us that in 1753, “at the sale of 
Commodore Lisle’s shells at Longford’s, four Wentle- 
traps were sold for £75 12s. ; viz., first day, February 
21, lot 96, one not quite perfect, £16 16s. ; third day, 
lot 98, a very fine and perfect one, £l8 18s. ; fourth 
day, lot 101, one for £16 16s. ; sixth day, lot 83, one 
for £23 2s. At the present day the value is very 
much reduced. 
The animals of some of the species exude a purple 
fluid when molested, and Montagu in his “ British 
Shells” has described the liquor discharged by the 
common species of the Mediteiranean, S. claihrus. 
As much can be procured, he says, from five indi- 
viduals as is sufficient, when mixed with a few drops 
of spring water, to cover half a sheet of paper. The 
colour at first was very bright, and appeared for some 
months unchanged by the action of the air or sun ; but 
being exposed for a whole summer to the solar rays, 
in a south window, they almost vanished. Like the 
lanthina, just mentioned, this Scalaria has been sup- 
posed by some naturalists to have been one of the 
shells employed by the ancients to furnish the celebrated 
Tyrian dye, b)it the same objections apply to it as to 
the purple fluid of the lanthina. ^ — See above. 
The remaining families of the Proboscidifera, 
Acteonidce, Cerithiopsidce, Pyramidellidce, and Archi- 
tectomidw (Solarium), are of no particular interest, and 
so Y/Q hasten on to the next sub-order. 
ROSTRIFEKA. 
The animals have a moderate-sized head, with a more 
or less elongated, produced, transversely-annulated 
rostrum, which is furnished with contractile muscles 
