At low tide also, look out for rocks with a number of round holes in them, all close together, for in these holes the Pholas ([Fig. 22]) dwells, having bored a burrow in the solid rock, though how he does it we do not yet quite know.
The Razor-shells and Cockles live in the sand, their presence being indicated by a small round hole; but they bury themselves so fast that you will find it difficult to get at them. Some good specimens, too, of the deeper water forms are sure to be found near the spots where fishermen drag their boats ashore, as they are often thrown away in clearing out the nets; moreover, if you can make friends with any of the said fishermen, they will be able to find and bring you many nice specimens from time to time.
The reason that so much has been said about collecting living specimens, is not only because in them the shell is more likely to be perfect, but also because in its living state the shell is coated with a layer of animal matter, sometimes thin and transparent, at others thick and opaque, called the periostracum (or epidermis), which serves to protect the shell from the weather, but which perishes with the animal, so that dead shells which have lain for some time tenantless on the ground, or at the bottom of the water, exposed to the destructive agencies that are constantly at work in nature, have almost invariably lost both their natural polish and their varied hues, and are besides only too often broken as well. Since, however, even a damaged specimen is better than none at all, such should always be kept until a more perfect example can be obtained.
HOW TO PREPARE THE SHELLS FOR THE CABINET.
The question with which we have next to deal is, after collecting a number of living mollusks, how, in the quickest and most painless manner possible, to kill the animals in order to obtain possession of their shells. There is but one way we know of in which this may be accomplished, and that is by placing the creatures in an earthen jar and pouring boiling water on them. With land, or fresh-water snails, the addition of a large spoonful of table-salt is advisable, as it acts upon them chemically, and not only puts them sooner out of pain, but also renders their subsequent extraction far easier. Death by this process is instantaneous, and consequently painless; but to leave snails in cold salt water is to inflict on them the tortures of a lingering death; while for the brutality of gardeners and other thoughtless persons who seek to destroy the poor snail they find eating their plants by crushing it under foot on the gravel path, no words of condemnation are too strong, since it must always be borne in mind that snails have not, like us, one nervous centre, but three, and are far more tenacious of life; hence, unless all the nerves are destroyed at once, a great deal of suffering is entailed on the poor creature; and if merely crushed under foot, the mangled portions will live for hours. Hot water has also the advantage of tending to remove the dirt which is almost sure to have gathered on the shells, and so helping to prepare them better for the cabinet. As soon as the water is cool enough, fish out the shells one by one and proceed to extract the dead animals. This, if the mollusk is univalve (i.e., whose shell is composed of a single piece), such as an ordinary garden snail, can easily be done by picking them out with a pin; you will find, probably, that some of the smaller ones have shrunk back so far into their shells as to be beyond the reach of a straight pin, so it will be necessary to bend the pin with a pair of pliers, or, if none are at hand, a key will answer the purpose if the pin be put into one of the notches and bent over the edge until sufficiently curved to reach up the shell. You will find it convenient to keep a set of pins bent to different curves, to which you may fit handles by cutting off the heads and sticking them into match stems. It is a good plan to soak some of the smaller snails in clean cold water before killing them, as they swell out with the water, and do not, when dead, retreat so far into their shells. If you have a microscope, and wish to keep the animals till you have time to get the tongues out, drop the bodies into small bottles of methylated spirit and water, when they will keep till required, otherwise they should of course be thrown away at once. The now empty shells should be washed in clean warm water, and, if very dirty, gently scrubbed with a soft nail or tooth brush, and then carefully dried.
In such shells as the Periwinkle, Whelk, etc., whose inhabitants close the entrance of their dwelling with a trap-door, or operculum as it is called, you should be careful to preserve each with its proper shell.
If you are cleaning bivalves, or shells composed of two pieces, like the common mussel, you will have to remove the animal with a penknife, and while leaving the inside quite clean, be very careful not to break the ligament which serves as a hinge; then wash as before, and tie them together to prevent their gaping open when dry.
Sometimes the fresh-water or marine shells are so coated over with a vegetable growth that no scrubbing with water alone will remove it, and in these cases a weak solution of caustic soda may be used, but very carefully, since, if too strong a solution be employed, the surface of the shell will be removed with the dirt, and
