Land snails exhibit a partiality for calcareous soils, not only by those living on downs and hill-sides, but also by the woodland species.
Having spent the forenoons of three days in gathering slugs and snails as before detailed, one evening was devoted to the preparation of the specimens for the cabinet.
The first step was to remove the animals, and, as all know, it is neither an easy nor a clean task to separate the living snail and its house; but kill your snail, and the muscular connection with the shell being severed, its whole body is readily taken out by means of a pin—why, it is just like picking periwinkles; and if the proclivities of our childhood's days are not entirely obliterated, cleaning out larger snails from their shells will be a task requiring no teaching. But, with regard to the smaller kind, it is another matter, and it will be my duty to show you how to set about the work.
Now pick out those shells, the apertures of which are wide enough, as it seems to you, to permit the removal of the dead body of the snail by a pin. You may also place with them the larger bivalves. All these we will boil to kill the animals; then strain off the water, and wash with cold water. By this means the bodies contract, and being firmer are not so liable to be broken in the process of removal. Shake the water out of the empty shell, and place them before the fire to dry; do not rub them, but particles of dirt may be gently flicked off by the aid of a camel-hair brush. Thus we treat the larger snails. Now for the mussels. Doubtless most of the dead bodies will have fallen out between the open valves while in the water; should any remain, a slight shaking of the shell held by the hand in the water will remove the contained body. Taken from the water, the valves gape widely; dry the inside and outside with a cloth, and having tape or cotton at hand, close the valves by the pressure of the thumb and fingers of the one hand, and with the end of the thread between your teeth, wind the thread two or three times around the shell with the other; now tie the thread as tight as you can. "Yes, I have done so, but still the valves are not closed." True, this is because of the elasticity of thread. If, however, you will take the precaution to wet the thread before tying, you will find that the tie is more secure, and that there is less difficulty in making the second knot.
With patience and a little skill, bivalves as small as Cyclas cornea may be treated in this way. But the smaller Pisidiums, and some of the minute snails, as Carychium minimum, may be prepared for the cabinet by gently drying them in sand; too great a heat causes a transfusion of the carbonaceous matter of the animal into the substance of the shell, which is thereby discoloured.
There still remain for treatment such shells as Clausilia, Bulimus, Helicella, some Helices, &c., the animals of which retreat, on the least irritation, beyond the reach of a pin, and whose shells, indeed, will hardly bear the rough handling almost necessary when a pin is used. Their bodies might be dried within the shells, but if it be possible to remove some portion only of the animal, an attempt should be made to do so.
Land snails, when placed in water, do their best to effect an escape from a medium so fatal to them; their efforts are usually exhibited by stretching out their bodies to the utmost, swaying them to and fro as if in search of a foothold. Taking advantage of this propensity, the snails should be immersed in tepid water, because the majority, after a day or two's confinement in the collecting boxes, will be in a dormant condition, and warm water has a greater resuscitating effect than cold. When all the snails are struggling to find a way out of their unpleasant situation, gradually add hot water so as to kill or paralyze them while in an extended state. They may now be thrown into boiling water, the better to relax the muscular attachments, and the bodies, or so much as will come away, dragged out by forceps, or a pin passed through the foot. The shells may now be dried in sand, as before mentioned.
In cleaning the shells of some species, great care is needed, so as not to remove the hairs or bristles which clothe the surface of the epidermis.
The shells of such snails as Paludina, Cyclostoma, &c., &c., would be imperfectly illustrated without the opercula or lids which close the apertures of their shells. Each one should be detached from the foot of the snail, the interior of the shell plugged with cotton wool, and the specimen gummed down in its natural position.
The preservation of slugs requires separate treatment, and I can give but little additional information to that published in my 'British Land and Freshwater Molluscs' an extract from which is subjoined:—