Shell (biology)

“ This substance is the production of the animal inhabiting the shell; it is uniformly observed in some species, and not at all in others. Shells with a rugged or uneven surface have almost always this epidermis. In some it is strong, laminated, velvety, fibrous, or rough, often beset with long hairs, and in others very thin, smooth, and pellucid, and admits the colours of the shell to shine through it. In some species it is so dusky that it entirely obscures the beautiful colouring of the shell beneath. ”

“ FORNICATED. Arched or vaulted, as the exfoliations on the costæ of Tridacna Elongata, fig. 157.
FOSSIL SHELL. A shell is considered to be in a fossil state when, the soft parts having ceased to exist, it is deprived of all its animal juices, has lost all, or nearly all its natural colour, and is thus changed in its chemical composition, when little or nothing is left but a mere bone, which is embedded in a sedimentary deposit. ”

“ The color-patterns of the shell vary to a wonderful degree. The young shell has a thin epidermis, a sharp lip to the aperture and a more or less prominent spire, the rolled over and toothed lip and polished surface not being acquired until fully adult. No more beautiful sight can be imagined than one of these gorgeous animals, as seen through the clear water, crawling over the sandy bottom or on the branch of some coral. ”

“ The protective shells of some animals, the epidermal appendages (horns, tusks, hoofs, claws, nails, hair, wool, etc.) , of others, are only alive at their proximal ends—their "roots" so-called. Their distal extremities are not living. They are products of life, but so are our coal beds, chalk cliffs, coral reefs and tortoise shell combs, but they are not alive. ”

“ Specimens.—The first thing that the amateur needs to learn about a shell is that it may be living or dead. As a general thing, what is technically called a "dead" shell is worthless in a cabinet. A live shell is one which has been collected with a living mollusc in it, and then duly cleaned, preserving all its beautiful colors. ”

“ Among the shell-bearing molluscous animals, the little shell which contains the creature in its youngest stages remains ever after as an integral part of the outer calcareous case. As the inhabitant grows, it continues to add band after band to the outer edge of the shell, each of which, whilst preserving the general symmetry and proportions of the whole structure, increases its dimensions in every way. ”

“ Not only is the interior of the shell made lustrous and beautiful, but this tendency is exerted toward all objects that come in contact with the soft body of the mollusk, either by intrusion simply within the shell, or deeply within the organs and tissues of the animal itself. ”

“ This you may easily prove by applying a little acid to a shell, and you will find that an effervescence takes place.
"The animals that inhabit shells are bloodless, without bones, but provided with a heart, lungs, and mouth, together with other organs needful to their conformation.
"Testaceous animals have the power of enlarging their habitations; they can also repair any injury that may occur to them.
"Many kinds of shell-fish are made use of by man, and form a valuable article of food, such as oysters, cockles, muscles, scallops. The whelk is also used, and a species of murex. ”

“ We next notice that these shells are precisely similar to those still found with living occupants in the river below, only they are no longer of a brownish colour, but owing to the loss of the animal matter of the shell have an earthy, dirty-white appearance. To carry these home they should be packed in bran in one of your tins with a note as follows made on a piece of paper and placed just inside—"Sand in gravel: topmost bed —— pit, August 2nd, 188-." Then if you are not able to work them out at once on reaching home, you will not forget whence they came. ”

“ Suppose that we begin our examination by looking at the hard case or 'shell' in which the soft parts of the animal are inclosed. We find on referring to the development of the animal, that this 'shell' actually represents the hardened skin of the animal, and that viewed in this light, it closely corresponds to the shell of the lobster or crab. The shell is flattened at each pole, and we can readily perceive that it is composed of rows of little limy plates, which are disposed in a regular manner from pole to pole, or after the fashion of the meridian lines on a globe. ”

“ Some or other of the members of this class are well known to everybody, if only in the shape of toothsome food—the Prawn, the Shrimp, the Lobster, the Crayfish, and the Crab. The great characteristic of this class of the Arthropod phylum is the so-called ‘shell,’ which differs greatly from true shell in being composed of chitine, hardened with salts of lime. Most of the species live in the water and breathe by means of gills or through the skin. In dealing with these creatures, some long words must be employed, if our present work on them is to be a stepping-stone to something more advanced. ”

“ We may always know the different species by the forms and patterns of the shells in which they live. Some have very regular shells and prettily marked. These are usually rounded or arched on one side and flat on the other.
When you are looking for various microscopic objects in pond water you will often see these tiny shells [90] among the sediment on your slides, and if you will patiently wait a few moments you will soon see delicate, transparent arms slowly pushing out on every side like cautious feelers. (Figure 2, Amœba in Shell.—Carpenter, p. 445.) ”

“ When live shells, as they are called, that is having the living fish in them, are obtained, the best plan is to place them in spirits of wine, this at once deprives the inhabitant of life, without injuring the shell, which should then be placed in hot water for a time, the body of the mollusk is thus rendered firm, and may be removed by means of some pointed instrument; care should be taken to leave no portion of animal matter within, or after a while it will become putrid and give out a stain, which will show through and injure the delicate markings of the shell ”

“ The transitions of these shells, it must be confessed are so various as to render it extremely difficult, if not unsafe, to determine where one species ends and another commences, the difference in the colours affords no sufficient data, neither is the form of the shell, nor the height of the spire so uniformly certain as to constitute a precise criterion. ”

“ The foot is free, flat, attached to the base of the neck. Shell spiral, and enclosing the animal when at rest. This order contains the families, Colimacea, Lymnacea, Melaniana, Peristomiana, Neritacea, Janthinea, Macrostomata, Scalariana, Plicacea, Canalifera, Alata, Purpurifera, Columellaria, Convolutæ. The genera belonging to these families, are represented in the plates, fig. 264, to 462.
TRANSVERSE. (Crosswise.) A shell is said to be transverse, when its width is greater than its length, that is, when it is longer from one side to the other than from the umbones to the ventral margins. ”

“ Many a living shell has an epidermis, the same as an animal, while a dead shell has none.
When shells are obtainable, who can resist the impulse to gather them? The man, woman, or child who is proof against the seductive powers of the beautiful and many-colored shells of the seashore "is fit for treason, stratagems, and spoils." Next to the pleasure of collecting shells one's self is that of witnessing the keen delight of children and ladies in gathering these beautiful treasures of the sea. ”

“ The second class embraces the mollusks, or animals inhabiting shells. They are destitute of a spinal marrow, and for the most part their muscles are attached to the external covering, called the shell, although this shell is sometimes internal. ”

“ If we imagine a delicate discoid spiral shell of elegant form, marked with curved and diverging grooves, and inhabited by a tiny piece of clear jelly without organs, but capable of projecting the substance of its body (called “sarcode”) in the finest possible filaments through perforations in the surface of its shell, this first principal representative of the deep sea soundings is before us. In our prepared and mounted specimen it is the shell alone which we see; the delicate tenant has of course long since perished, and its beautiful envelope alone is left ”

“ The shell is shaped something like that of a whelk, but is very smooth and porcelain-like, and is generally white, ornamented with several coloured bands. It is, however, one of the most variable of shells, differing not only in colour but in form. It always inhabits the belt of the shore between tide-marks, and preys upon other Molluscs, such as the mussel and periwinkle, literally licking them to pieces with its long riband tongue. ”

“ Testacea (L. testa, a shell) . Molluscs with a shelly covering, as the Oyster, Whelk, &c.
Univalve (L. unus, one; valvæ, doors) . A shell composed of one calcareous piece, as the Periwinkle.
Umbones. The base of a shell about the hinge.
Viviparous (L. vivus, alive; pario, I bring forth) . The animals which bring forth their young alive. See Oviparous.
Whorl. The spiral turn of a shell.
Zoology (Gr. zoon, animal; logos, a discourse) . That branch of science that treats of the habits, structure, and classification of animals.
Zoologist. One who is acquainted with the science of Zoology. ”

“ Try, too, to get young forms as well as adult, for the young are often very different in appearance from the full-grown shell. Mark on them, especially on such as you have found yourself, the locality they came from, as it is very important to the shell collector to know this, since specimens common enough in one district are often rare in another. Either write the name of the place in ink on a corner of the shell itself, or gum a small label just inside it, or simply number it, and write the name of the place with a corresponding number against it in a book kept for the purpose. ”

“ The smaller figure in the lower part of our plate is a representation of the same species in its usual form, and appears clothed or covered with the thick filmy epidermis, of a brown colour, with which the shell is naturally covered when in a living state. From this figure it will be perceived that the direction of the spiral wreath or whorls in the larger shell is exactly reversed, and that the mouth or aperture of the shell, which in the smaller figure appears on the right side, is seen in the reversed shell on the left. ”

“ The shelly or membranaceous plate with which some of the animals enclose the aperture of their shells, during the wintry part of the year, for the purpose of protecting them while in a torpid state, and which they get rid of by dissolving the edges, when preparing to emerge from their temporary retirement, must not be considered as the operculum, as it does not belong to or form part of either the animal or its shell, but is produced for the occasion by a secretion of the animal, being deposited in a soft state and subsequently hardening. ”

“ First, The entire shell, (Pl. 35,) is one continuous arch, coiled spirally around itself in such a manner, that the base of the outer whorls rests upon the crown of the inner whorls, and thus the keel or back is calculated to resist pressure, in the same manner as the shell of a common hen's egg resists great force if applied in the direction of its longitudinal diameter. ”

“ Respecting the construction of the shell it may be observed that it is produced in the thickness of the mantle, or cloak-like covering which envelopes the body of the animal; the formation commences at the small end or spire, and gradually goes on, whorl upon whorl, as the still widening circles which give the ridgy appearance to most univalves, are called. ”

“ Although shells take on many different shapes, they are much alike inside. Each has a foot, a breathing siphon, a tiny brain and heart, and a fleshy mantle which secretes lime for shell-building. Most true mollusks have eyes, but a few are blind. ”

“ Well, because this is a hobby and science that spans the world. Englishmen, Frenchmen, Greeks and Indians all have their own local names for shells. But scientists everywhere give things in nature Latin names. Shells of the same sort carry the same Latin label on every beach in every sea. Much of the fascination of shell collecting is learning these names and how they were derived. . . for shells have been named for almost everything. We can't catalog 100,000 species here, but let's call off the names of a few of the interesting specimens you might come across. ”

“ It is pronounced tes-ta-shus, comes from the Latin testaceus—having a Shell, and means consisting of, or composed of shells; so we find that a testacean is a shell-fish, and testaceology is the science of shells. Johnson’s second meaning of the word testaceous is ‘Having continuous, not jointed shells, opposed to crustaceous.’ So we find that some naturalists call those testaceous fish, “whose strong and thick shells are entire and of a piece, because those which are joined, as the lobsters, are crustaceous.” ”

“ The Cancellariadæ, in which the shells are cancellated or cross-barred by a double series of lines running, one set with the whorls, and the other across them.
3. The Pyramidellidæ, which are high-spired, elongated, and slender shells, with the exception of the genus Stylina, which lives attached to the spines of sea-urchins or buried in living star-fishes and corals.
Fig. 12. Cypræa oniscus.
4. The Solaridæ or "Staircase-shells," whose umbilicus is so wide that, as you look down it, the projecting edges of the whorls appear like a winding staircase. It is a very short-spired shell. ”