Snail shell

“ Where the ground is made of chalk or limestone, they will be found most abundant; for as the snail's shell is composed of layers of animal tissue, strengthened by depositions of calcareous earthy-matter which the creature gets from the plants on which it feeds, and these in their turn obtain from the soil—it naturally follows that the snail prefers to dwell where that article is most abundant, as an hour's hunt on any chalk-down will soon show. ”

“ Fig. 95.—The recently removed canal mud, in the upper section of the illustration, is heavily charged with large snail shells. The lower section shows the shells in the soil of a recently spaded field.
Several species of these snails are collected in quantities and used as food. Piles containing bushels of the empty shells were seen along the canals outside the villages. The snails are cooked in the shell and often sold by measure to be eaten from the hand, as we buy roasted peanuts or popcorn. ”

“ 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. ”

“ Drawings to show the pond snail in various positions in the aquarium. A drawing of the slug. At least three different types of snail shell. Summary. In what respects does a snail show resemblance to a clam? What are the chief points of difference? What reasons can you suggest for the better development of the sense organs? What advantage has a snail over a clam in the matter of getting food? How does the shell of the snail compare with that of the clam as an organ for protection? ”

“ This partition is again lined with a silky membrane. The snail then retires a little further into the shell and forms a second membranous partition, retiring again and again until there are six of these partitions between the snail and the lime-coated door at the entrance of the shell. In the recess behind all these partitions the snail lies torpid until May. All this time it lives without motion, without heat, without food, without air, without circulation or the exercise of any of its functions. ”

“ Motion, slow at the outset, became more difficult, and the protection of the shell therefore all the more necessary. The shell increased in size and weight and motion became almost impossible. The snail represents the average result of the experiment. It can crawl, but that is about all; it is neither swift nor energetic. Even the earthworm can outcrawl it. It has feelers and eyes, and is thus better provided with sense-organs than almost any worm. It has a supra-œsophageal ganglion of fair size. ”

“ On robes it is spiral from right to left and from the center outward, each year being added to the coil as the snail adds to its whorl. The spiral line, frequently seen in etchings on rocks, has been explained to me as indicating a snail shell. On paper they are sometimes carried from right to left, sometimes from left to right, and again the two methods are combined as in Battiste Good’s winter-count, which begins at the back of the book and is carried forward, i. ”

“ 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. ”

“ Nearly all sea-snails, that is, snails which live in salt-water, and many species of fresh-water snails, and also many snails which live in damp places on the land, and which are called land-snails, have an operculum. "When the snail has retired within the shell, the operculum will look like this in the aperture of the shell (Fig. 6) : A series of concentric lines will be seen marking the operculum, and these are the lines of growth, the operculum growing around the outer edge by successive additions, just as the shell grows by successive additions to Its outer margin. ”

“ 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 ”

“ One of the most humorous sights in nature, less common in America than Europe, is a snail wandering about with a shell on its back. The progenitors of snails once lived in the sea, and when they evolved themselves ashore they carried this relic of the water with them,—an anomaly which, seen to-day, seems as ridiculous as if one were to meet an Indian in Paris with his canoe on his back. But there are more animals besides snails that once lived in the water. If embryology is any guide to the past, nothing is more certain than that the ancient progenitors of Man once lived an aquatic life. ”

“ Up goes his head, lifting the snail high in the air, and then, smash! the shell comes down on the stone with all the force he can use. About two such blows break the shell, and he then coolly chips the fragments off as you might from an egg, and makes very few mouthfuls of the contents. On the stone and round about it lie the fragments of many such shells—relics of former feasts. Sometimes he will do this close to the bay-window—if all is quiet—using the stone-flags for an anvil, if he chances to find a snail hard by; but he prefers the recess behind the box-hedge. ”

“ The young animal gnaws its way out of the egg, and makes its first meal out of the shell it has just left, and is then a snail of about a whorl and a half. But it grows very fast. It begins to prepare for hibernation at about the first frost, by ceasing to feed, becoming inactive, and fixing itself to the under surface of the substance by which it is sheltered, or burrowing a little way into the soil. The aperture of the shell looks upward, and the snail closes it by forming a glutinous shell-substance over it which is called the epiphragm. ”

“ Every conchologist takes it for granted, of course, that the shells which he receives from foreign parts have had their inhabitants properly boiled and extracted before being exported; for it is only the mere outer shell or skeleton of the animal that we preserve in our cabinets, leaving the actual flesh and muscles of the creature himself to wither unobserved upon its native shores. At the British Museum the desert snail might have snoozed away his inglorious existence unsuspected, but for a happy accident which attracted public attention to his remarkable case in a most extraordinary manner. ”

“ The shells of the dead snails are soon covered with a thick calcareous crust, which continually increases as the years go by, forming cones of various sizes until the uninitiated would hardly suspect that the resultant mass had once been a snail-shell. A day was also devoted to photographing the magnificent waterfall (Plate IV) . In order to descend the steep walls of the ravine in front of this waterfall, we had to tie ropes to the trees. ”

“ The Helicidæ, or Helix family, is that which includes the land shell Snails and the naked Slugs, and in this family there are several genera; they are distinguished from the shelled water Snails, both sea and river, by having a different breathing apparatus, and some other points of internal construction which it is not necessary to describe here.
The Common Snail has a mouth, of which it makes good use, as market gardeners well know, and yet this mouth is not furnished with teeth ”

“ Univalves, that is to say shells which consist of one piece, are those of the snail-like animals, Gasteropoda, or Gastropoda, as some prefer to spell it. Bivalves, or shells which consist of two flaps, are those of the Lamellibranchiata or animals with plate-like gills, such as the mussel or oyster.
Let us begin with the former. Everybody knows the snail. The snail proper bears a typical univalve shell: though in its relatives (the slugs) , the shell is more or less suppressed. ”

“ Indeed up to the present day in many of our provincial dialects slugs and snails are invariably both included under the latter name; the snail proper being sometimes distinguished from the other as the ‘shell-snail’ (see Holland’s Plutarch, p. 212) . See an interesting discussion in the Philological Society’s Transactions, 1860-1, pp. 102-106.
There is much variety even in creatures of the same kind. See these two snails. One hath a house, the other wants it ”

“ It fixes itself on the edge of the shell, with the aid of its sucker, and directs its strong mandibles to the side on which the snail is obliged to raise the covering, either to breathe the air or to walk. In this position it has the patience to wait for 512 many days at the door. The snail puts off for as long a time as he is able the fatal moment. ”

“ Let us now return to the Glow-worm. When the Snail is on the ground, creeping, or even shrunk into his shell, the attack never presents any difficulty. The shell possesses no lid and leaves the hermit's fore-part to a great extent exposed. Here, on the edges of the mantle, contracted by the fear of danger, the Mollusc is vulnerable and incapable of defence. But it also frequently happens that the Snail occupies a raised position, clinging to the tip of a grass-stalk or perhaps to the smooth surface of a stone. ”

“ In the woods you see yellow ones with several black bands wound round them in regular order.”
“The creature we call the spiral snail—isn’t it a slug that finds an empty shell and lives in it?” asked Emile.
“No, my friend; a slug remains always a slug without becoming a snail; that is to say, it never has a shell. The snail, on the contrary, is born with a tiny shell that grows little by little as the snail grows. The empty shells you find in the country have had their inhabitants, which are now dead and turned to dust, only their houses remaining.” ”

“ The snail must be rapidly digested in the stomachs of birds generally, as in some hundred cases that have come under my examination the internal shell alone has borne witness to its having ever been there. ”

“ Another species (Osmia bicolor) sometimes makes its cells in very peculiar situations. When obliged to have recourse to its natural powers, it uses its limbs right well, attacks the hard sandy banks, and works at them with the greatest perseverance. But it will not work one stroke where it can avoid the necessity, and in many cases, it contrives to avoid work with much ingenuity.
Lying hidden under hedges, bushes, grass, and herbage, are sure to be shells of various snails, such as the common garden-snail, and the banded-snail, whose diversified shell is the delight of children. ”

“ This little creature, in spite of his formidable name, is, in fact, a very harmless fellow, of the lizard race, and about ten inches in length. It lives on trees, and devours insects that come in its way. It is found in Asia and Africa.
The Snail.
This creature, apparently so insignificant, is one of the greatest curiosities of nature. The animal consists of a soft, pulpy substance, with a curious shell, [Pg 109] which serves as a house, and to which it always is attached. When the snail wishes to go from one place to another, he drags his shell along on his back ”

“ There was in this same mountainous district a species of snail, [2287] furnished with a shell in winter, which appears to have been both eaten and used as a medicine.
In many parts of Italy they still make use of snails for the same purpose, digging them up out of the earth with an iron instrument. The ancients kept tame snails for eating, which they fatted with a mixture of flour and sweet wine. [2288] In France they are still fed on vine leaves [2289] in cages, where 372they attain an immense size. ”

“ The former is a handsome snail, with a bronze-tinted, globular shell; the latter has a spiral form. These will readily reduce the vegetation. And to preserve the crystal clearness of the water, some Mussels may be allowed to burrow in the sand, where they will perform the office of animated filters. They strain off matters held in suspension in the water, by means of their siphons and ciliated gills. ”

“ One can readily understand, at all events, how snail-shells might be swept down the slopes of the land at the time of the spring thaws, and how large numbers might find their way eventually into the swollen glacial rivers. I have often observed, during the melting of snow and the thawing of soils, quantities of snail-shells in the very act of being swept into our brooks and rills. And we are all familiar with the fact that, after a spring-flood has subsided, snail-shells, along with vegetable débris, are often plentifully stranded upon the valley-slopes and flood-plains of our rivers. ”

“ On the whole, I am not disposed to think my shell is here described, and put my splendid book in its place again.
I next try my English Cuvier, in sixteen octavo volumes; in which I find no notice whatever taken of these minor snails, except a list of thirty-three species, finishing with an etc.; out of which I mark ‘Cretacea,’ ‘Terrestris,’ and ‘Nivea,’ as perhaps likely to fit mine; and then I come, by order of Atropos, on this amazing account of the domestic arrangements of a little French snail, “Helix decollata” (Guillotined snail?) with references to “Cm. ”