J. W. Horsley

“ I differ from the Gasteropoda (whether they be terrestrial or aquatic) in that I and my near relations are exclusively aquatic and of a sedentary life, which makes the protection of two encompassing shells necessary. These shells are secreted by my mantle lobes, and are united by a ligament which tends to make the valves ‘gape’ for water and food and by two contracting muscles which close them in danger. I have a degenerate brain and no eyes. My mouth has neither jaw nor teeth, but possesses nervous lips covered with cilia, the vibration of which carries food-laden water to my mouth. ”

“ Nemoralis is fond of sand-hills by the coast, but is chiefly a hedge-snail, and the edges of main roads are preferred because of the greater variety of food, because the traffic scares away their bird enemies, and because the dust gives them abundance of already prepared material for their shells. When, however, the collector comes to a wayside cottage where fowls are kept he need not waste his time in looking for snails in the neighbouring hedge. The more the chicken industry extends and the more the Bird Protection Acts operates, the worse it is for collectors of snails. ”

“ Get into the way of carrying a note-book with you to record not only what shells, or varieties of a species, are found in any particular spot, but also anything you observe as to the habits or peculiarities of the objects of your search. ”

“ A snail may possess over twenty thousand tiny flinty teeth set on a ribbon so as to make a mowing-machine for the vegetable matter on which it feeds. With its aid also you might study the life-history of a mollusc from the egg onwards, and be able to determine by minute anatomical points whether two molluscs were of the same species or not—a matter in which the shape or appearance of the shell is not always a safe guide. ”

“ H. itala, virgata, etc., are fond of a newspaper for food rather than for shelter.
During the hibernating season, which extends from November to April, we turn rather to ditches than to hedges, and, armed with a perforated scoop at the end of a long stick, we dredge among the water-weeds, or sift, like gold-washers, the sand or mud in ditches, ponds, and backwaters [Pg 19] of rivers. Here we are introduced to the great bivalve family which is unknown on land, and our trophies range from the freshwater mussels, as large as our hand, to others hardly larger than a pin’s head. ”

“ The body of this species is cobalt blue, the apex of the shell is flat, its colour opaque, and the last whorl more expanded than in others. All belong to the sub-genus Polita, and have polished or glossy shells. All love shade and moisture, and should be sought under stones or wood or in moss. They only come out by day when it is wet, a habit they may have acquired from their being a favourite food of birds, 416 having been found in the crop of one nestling Stockdove; while various flies are very destructive to them. This species prefers animal food, and is more gregarious than others. ”

“ B is the body, soft and with a surface generally wrinkled or covered with small tubercles. F is the foot or muscular pad which forms the foot by the wavelike contractions of which it moves. H is the head, bearing the tentacles T1 and T2, of which the upper pair have the eyes, E. The mantle, M, makes the shell by secreting lime, etc. In it is the breathing orifice, BO, obvious in the slug, but in the snail nearly hidden by the shell. L in the snail is the spiral part, the liver, and it occupies a large part of the shell. ”

“ Thrushes and mice are its great enemies, the former smashing it on some stone which may be found surrounded by the broken shells. The “mouth” or peristome is normally black, the shell larger and stouter than hortensis, in which the mouth is white. When a white-mouthed nemoralis or dark-mouthed hortensis (both rare) is found, the shape of the internal flinty dart at once distinguishes them. In some places both live together: in most one is found and not the other. ”

“ Looking backwards we, therefore, place our friend as the species aspersa, of the sub-genus Pomatia, of the genus Helix, of the family Helicidæ, of the sub-order Pulmonata, of the order Inoperculata, of the sub-class Gasteropoda, of the class Cephala, of the sub-kingdom of Mollusca, of the kingdom Invertebrata or backboneless animals. ”

“ A spiral shell of 4-1/2 whorls, suture very deep. Mouth circular (whence its name) and provided with a thick shelly operculum which closes the orifice when the animal retires by means of an elastic ligament. This and the next species are our only land shells provided with an operculum, and this shows their derivation from the marine Gasteropoda (e.g. whelk and winkle) . Perhaps all shells were originally marine, but some became first amphibious and then terrestrial. It is quite unlike any other of our land shells.
Acicula lineata is a very small shell, the size of the Pupæ ”

“ A hedge-snail. White forms not uncommon, though almost unknown in nemoralis. Though the weaker form, the coalescence of the five bands into one broad one is more common here than in nemoralis. Also the variety with only one band, and that on the periphery, is very common in nemoralis and rare in hortensis. It is more dependent on shade and moisture than its congener. Smells of garlic when immersed in boiling water to be killed. Hortensis is a more northern, and nemoralis a more southern, shell by origin and distribution. ”

“ In the class of Cephala, to which our snail belongs, there is the sub-class of Gasteropoda, or stomach-footed, because on the ventral side of the body a sole-like disc or foot exists, by the wave-like expansions and contractions of which the animal progresses.
In this sub-class there is a division according to their having or not having an operculum, or means of closing and protecting the orifice of the shell. Most gasteropods which live in water have this; most which live on land (only [Pg 25] two exceptions in British molluscs) have not. ”

“ A heart of two chambers, veins, arteries, and blood our snail possesses, and, like man, the old snail has a slower pulse than the young one, and in both exercise increases the pulse rate and also warmth. Breathing is accomplished by a single chamber or air-cell, but also through the skin. As in the case of plants, some kinds are male and female separately, and as some have both powers and products in the same plant, so also is it with mollusca. H. aspersa and most Gasteropoda are of the latter kind. ”

“ This can be done by holding your thumb nearly over the mouth of a watertap, while the shell is held in the left hand. Only adult shells should usually be taken, and those which are weather-worn or bleached should be neglected. In most the lip, or opening, of the shell will be hard if adult, and membranous if young; but experience alone will enable you to discriminate, especially where the young of one species is like the adult of another. ”

“ Thus the slug Limax gets its name from limus, “mud”; but a scientist, who ought to have known [Pg 12] better, when wanting a name for another kind of slug, transposed the initial letters and made Milax! Vitrina is a sensible and descriptive name, the Latin for glassy, given to a shell like thin glass; but the Greek Arion recalls either a certain musician or a certain swift steed, neither of whom naturally suggests a slug. ”

“ The power of taste they possess, as is shown by the preference of some foods to others. The sense of touch is acute and resides in all parts of the soft and moist external skin, and especially in the upper tentacles or horns in the Helicidæ. Jaws they have with which to seize and to bite off food, and in H. aspersa and others these bear teeth, but the chief work is done by a sort of toothed tongue, the radula, which rasps off particles of food with a side to side motion of the head as the animal advances. ”

“ In the former case, if an operculum (with which some species, both marine and land, close their mouths, more or less partially) exists, it will, generally in the case of land shells, remain in its place, adhering to the shell. In the latter, the decayed matter should be washed out, and the operculum, if any, replaced and fixed, say, on cotton filling the shell. This applies equally to land shells.
3. Care should be taken not to injure the edge or lip of the mouth of univalves, or the ligament of the hinge of bivalves. ”

“ The animals of Land and Freshwater shells may be killed by immersing them for a few minutes in boiling water, after which the bodies may be easily extracted whole with any suitable instrument, e.g., a fork or a pin, according to size. Hot water should not be used with marine shells: it often destroys their lustre. ”

“ Bivalves generally at the bottom, among stones, or buried in the sand, or among the roots of aquatic plants.
3. Land Shells.—These resemble, more or less, in their habits the garden snail, though varying greatly in character, size, and colour. They mostly abound in a chalk or limestone district, and in moist and wooded situations. Some species inhabit low and damp spots, roots of trees, hollows and crevices of rocks and walls; [Pg 67] some lie under stones or pieces of wood, or in the earth; others climb shrubs, and in tropical climates even lofty trees. ”

“ The habits of observation, of comparison, and of method, are those which all naturalists and collectors must have; habits which are of great value in other ways as well. Firstly, one must have the seeing eye, and train it to notice what many people do not. ”

“ Note also that most slugs have many variations in colour and markings.
Testacella haliotidea.—This genus of slugs forms a link between the naked slugs with rudimentary shells within, and the snails which live within their shells. The name Testacella, or little shell, was given by Cuvier in 1800, because this slug has a small shell at the end of the tail. Haliotidea means having a shell in the form of the marine shell Haliotis, the meaning of which again is the ear-shaped seashell, often called “Venus’ Ear.” It is subterranean in habit, and lives on worms. ”

“ Hurdles leaning against a hedge are often found to bear a good crop of snails. Damp places must be sought in dry weather; but a rainy day, that troubles some kinds of naturalists, sends the conchologist forth rejoicing, especially if a warm evening follows a wet day. A night search with a lantern will often be profitable. Where they will be undisturbed, traps may be set, such as flat pieces of wood (the older the better) , or cardboard, lying on the grass; while most of those species that belong to the group which seems to prefer the sun, e.g. ”

“ It contains specimens of all the British land shells with the exception of the slugs, which (with the exception of one of which I shall speak in its place) have no external or covering shell, although a small sort of shell, or at any rate some chalky grains, is found inside most of them. You would see that some are as small as a pin’s head although full grown, and they would require a magnifying glass to distinguish one from the other. The largest is Helix pomatia (figured on pp. 11 and 12) , which often goes by the name of “the edible snail.” All snails are edible and nutritious ”

“ Our aspersa has 12,615 teeth on this ribbon, [Pg 28] contained in 145 transverse rows. The organs of digestion are complex and practically much the same as our own. Little vegetation would be left in nature had not, on the one hand, snails been kept down by many enemies as well as by their need of hibernation and their short life; while on the other by numerous devices in the course of ages many plants have protected themselves against the moving machine of a snail’s mouth. Cultivated plants, which generally lose their natural protections, have to be guarded by human guards or gardeners. ”

“ With the exception of H. pomatia it is the largest of our native shells, and is too common to satisfy gardeners. A powerful animal of its kind, it can travel a yard in twelve minutes, or at the rate of a mile in a fortnight, can bear or draw on level ground a weight fifty times its own. ”