172 LAND AND FRESH WATER MOLLUSCA.
Amongst the aquatic species some, like Unio and Limnaea, affect
the mud at the bottom of rivers and ponds; others, like Neritina,
prefer the gravelly bed of a stream, or attach themselves to stones
like the fresh-water limpet Ancylus, or to the underside of the leaves
of aquatic plants like Physa and Succinea.
These can only be collected with a small dredge or landing net.
With a little muslin bag upon a brass ring six or eight inches in
diameter, fixed at the end of a fishing rod, a great variety of species
may be brought to land. As many of them have very thin delicate
shells, they require to be handled with great care, and should be
placed with a little cotton wool in pill boxes or chip boxes, on the lid
of which may be briefly noted in pencil the habitat and date. After-
wards, when the species has been properly identified, the scientific
name may be added.
As to the mode of preparing specimens for the cabinet, the animals
should be killed with boiling water, in which some common salt may
be usefully dissolved, and removed carefully from their shells by the
aid of a bent pin or similar contrivance. Those which on death
retire too far into their shells to be reached by this ordinary expedient,
such as Clausilia, Bulimus, and others, may be killed by placing
them in tepid water, and adding gradually hot water; the animals
may then be partially removed. The shells should be well dried to
remove the moisture and harden the soft parts remaining; but the
heat must not be too great, or else the shells will be discoloured, and
rendered liable to be broken; and, further, the specimens should be
well dried before placing them in the cabinet, which should be in a
well ventilated place, free from damp; for the freshness and beauty
of shells are apt to be lost by the growth of fungi upon their surfaces.
In cleaning the shells of some species, such as Helix hispida and
leaves, grub under the clumps of ferns and wood-rushes for small Helices, Pupae. and the like ;
scan the trunks of the trees for climbing Clausiliae, Bulimi, and Helices, not unmindful that each
little dirt-like mass is probably a Bulimus obscurus, which by covering its shell with mud, thus
exhibits a protective faculty, and often escapes detection. Raising the rotting bark for Balia ; lift
the stones at our feet or roll away a log for Helicella [Zonites] and other small shells which usually
live in such situations." It may also be worth while to quote the following passage from Dr. James
Lewis's "Instructions for Collecting Land and Freshwater Shells," issued by the Smithsonian
Institution (Washington, U.S.A.) :—" In and around dilapidated buildings, where fragments of
bricks and mortar cover the ground, large numbers of the smaller species of Helix, Pupa, Cary-
chium, etc. [of course he is referring to the American fauna] will be found. They adhere to the
under surface of a porous brick in preference to a fragment of gneiss, limestone, or other rock.
Also the cavity of a decayed tree or stump, when examined in the early days of spring, will reward
the searcher abundantly. Rich harvests may also frequently be gathered by laying boards upon
the grass or ground, wetting them previously, unless immediately after rain. On taking them up
after a night's exposure, large numbers of shells will often be found attached to the under
surface." Mr. Laver has referred with approbation (Trans. E. F. C. ii., p. 94), to the plan of
sifting leaves and rubbish from damp places in woods in a brisk current of wind, spreading the
heavier portions left over white paper, and thus easily detecting small species of shells, which
would otherwise be overlooked.—Ed.