Mary Anne Venning

“ Lately, we find a few of the small species are become a new genus, Trivia.
"The character of the Cypræa is a longitudinal aperture, toothed, in the adult state, on each side. The spire is scarcely to be seen.
"While the shells are young they have the appearance of a Voluta or a cone; the aperture spreads more, and is without teeth.
"The individuals of each species pass through three different states:
"In the first, the form is very imperfect; it is like a thin cone, and shows no character of the genus; hence young students are perplexed if they chance to have a young cowry in their collection. ”

“ Our example, Solen siliqua (Plate 1) is a British species. The hinge is not in the centre of the shell, but nearer to one end of it. Some are shaped like the handle of a knife or a razor, others are bent resembling the blade of a scimitar. The Solen lives in the sands of the sea-shore, often burying itself two feet deep, and retaining its shell in a vertical position: thirty-five species.
"The genus Tellìna is remarkable for the beauty of the shells, and, according to the arrangement of Linnæus, contains ninety-seven species. ”

“ There is a great similarity between the genera Turbo and Trochus. You must observe the generic distinction carefully. Shell univalve, spiral; aperture contracted, orbicular, entire. The one hundred and sixty-seven species have been much divided by other writers. The golden-mouthed Turbo is a very fine shell. This genus also contains the common periwincle, an inhabitant of most European shores. Sailors report that if the animal is seen creeping high up the rocks, it foretells stormy weather. Turbo muricatus is a pretty shell. ”

“ Elliot; "Pholas is another genus of the same division; it has the appearance of a bivalve. In the Chiton are several lamina, or plates, which are connected by a membrane while the living animal is in the shell; the membrane is pliant, and the inhabitant has the power of contracting itself into a ball, when it would avoid injury, like the insect millepes, that we find under stones in damp places. (Plate 2.) The curious barnacle-shell, Lepas, is another multivalve." ”

“ STROMBUS.
"The genera are three—
"In the first genus the shells are terminated below by a canal, or pointed beak; the right-margin entire, or toothed, more or less dilated with age, and having a sinus contiguous to the canal. There is a specimen from our own coast, Rostellaria pes-pelicani, the pelican's-foot: it was Strombus of Linnæus. (Plate 7.) There are many of this species found in a fossil state.
"The Pterocera genus is easily known by the digitated, or fingered, appearance of the right-margin. The greater part of the species become very large. ”

“ Within a few years, conchology has become a study of considerable importance, from its close connexion with geology. Students in the latter science must be well acquainted with fossil-shells, because they form so large a portion of organic remains. Species of recent shells, or those still existing, are also often found in a fossil state, while many fossil genera are now totally unknown in our earth and waters. ”

“ Generic character: shell equivalve, convex, ribbed, striated, or grooved, the margin toothed: hinge with two teeth near the beak, and a lateral one on each side: fifty-four species.
"Observe how the beaks of this common Cardium, cockle, turn inwards, and the bosses project. Another striking character is the ribs, that are generally longitudinal, and not concentric or transverse, as in Tellìna, and, as you will see, in Venus. C. aculeatum has small spines on the valves; C. costatum, the ribbed cockle, is one of the finest species of this genus, and C. cardissa is a beautiful shell. ”

“ A very few species are natives of the European seas.
"The tiger-cowry is before you; a large and very common species in collections; it also frequently adorns the mantel-piece. There is a remarkable line extending along the back of the shell; at this part the edges of the mantle, that I have before noticed, meet: this line is conspicuous in many species.
"C. aurora is a costly shell from Otaheite and New Zealand; the colour orange, with the base and extremities white. It is large, and has been sold for 60l. when a specimen has been obtained without any perforation. ”

“ The genus Corbis is fossil, with one exception, Corbis fimbriata, from the Indian Ocean. Lucina is a pretty genus of shells. L. carnaria is frequently found in collections. The interior of the valves is of a deep red colour: the muscular impressions are very distant from each other; one is greatly lengthened out; the valves delicately striated. Capsa is taken, you perceive, from Donax.
"Tellina is found fossil on the borders of the Red Sea, also in the county of York. Of Donax and Mactra the fossil species are few. ”

“ You are well acquainted with Patella, the limpet: one species of this genus is very common on the rocks by the sea-side. (Plate 1.) In the Patella genus we lose sight of a spire; the shell is nearly conic, and shaped like a basin. The species are very numerous, exhibiting great variety of form ”

“ The species are covered with an epidermis, sometimes very thick; the spire has various degrees of elevation, sometimes almost flat; the operculum very small and horny. They are natives of southern and tropical seas: the animal is carnivorous: found in sandy mud, at various depths of the ocean. The species are very numerous—Lamarck makes 181 recent. Some new species have lately been discovered. Many of the cones are very beautiful, both in shape and colour, and the genus has been always in estimation among collectors. ”

“ Many species are prettily marked by nature, others are rendered handsome by polishing. O. subulata is small, and pointed like a mitre. The common olive is white, with brown, waved lines. O. irrisans is ornamented with yellow zigzag lines: it has two brown zones. O. oriza, the little rice-olive, is white.
"I should have noticed the small genus Ancilla, formerly Ancillaria, which is very near both to Terebellum and Oliva. The columella has a varix at the base, which distinguishes it from Terebellum, and it wants the canal which separates the volutions of Oliva.
"There are several fossil species. ”

“ The body is soft, without joints, without head or eyes; it is wrapped in a mantle or tunic. The mouth, always hidden in the tunic, is merely an opening to admit food, without jaws or teeth. The shell is always bivalve; the valves united « 45 » by a hinge or a ligament; sometimes there are accessory pieces to the valves. ”

“ The species are determined by the margins. Some of the Chiton genus are common upon our own coasts; they are frequently found among seaweed and stones, rolled up like a ball. C. fasciculàris and C. lævis are British; there are some other British species. The animal adheres to rocks, like the Patella, or limpet. The number of species forty.
"Second genus, Lepas. Shell multivalve, fixed at the base; valves erect, or upright.
"Observe how much the situation of the valves differs in Chiton and Lepas. It is scarcely possible to mistake the one for the other. ”

“ Several are found on British coasts, but they are not remarkable for beauty.
"The top-shell, Trochus, is univalve, conic, spiral; the aperture either angular or rounded; columella oblique: some of the apertures have a tooth-like projection. (Plate 7.) Species, one hundred and thirty. Several kinds occur in « 34 » Britain. New Zealand, Friendly Isles, Red Sea, and most other seas, afford the various species. Two of this genus have the power of collecting parts of shells and other testaceous substances, which adhere strongly to the whorls of the shell: it is called the Conchologist. ”

“ C. marmoreus is a fine shell. Numerous species are within reach of your purses, and I do not doubt that you will soon acquire a good collection « 100 » at a moderate price. You, Charles, will find more pleasure in a cone than in a top; and Lucy, who never found much pleasure in toys except in taking them to pieces, has always a ready sixpence either for a poor neighbour in distress, or for some harmless pleasure. ”

“ The muscles that fasten the animals to their shells are thick and strong; their use is, to close the valves by contracting; when the muscle is relaxed, the elastic ligament is sufficient to open them. The Conchifera are all aquatic; some inhabit fresh water, the others dwell in the sea.
"The class contains nineteen families and two orders. The first order, Bimusculosa, contains thirteen families. The first includes genera that you will scarcely expect to find among the bivalve shells. ”

“ The first genus is found in the seas of warm climates. The shells are thin and foliated. The hinge of Perna differs widely from that of the oyster. It is linear, formed of sulcated teeth. There is a sinus under the extremity of the hinge, for the passage of the byssus. Compare P. isognomon with the common oyster, and you will find few points of resemblance between them. (Plate 5.) Perna ephippium is also a curious species, very pearly within. The hammers are rugged and singular in form. ”

“ A rich purple tint is very frequent in these shells. Donax denticulatus and trunculus are common British examples. (Plate 4.) You must remark the ligament of Donax, which is exterior.
"Our next genus ranks highest for beauty among the bivalves, and takes its name from the goddess Venus. The species amount to one hundred and sixteen in the Linnæan system, but other authors have formed several new genera.
"Shell bivalve, having the lips incumbent on the anterior margin; hinge with three teeth, all approximate, the lateral ones diverging at the lip. ”

“ Lateral teeth are situated on the sides of the valves, and are generally long and flat, sometimes hollow. Some hinges are straight, others curved. Here is the hinge of Arca, furnished with many small teeth. (Plate 3, b.)
"The ligament is a membrane that connects the valves, and keeps the hinge in its proper place: it is always situated near the beaks. The ligament is very perceptible in the cockle, in Pecten, or scallop, in Tellina, &c.
"The beaks are the most pointed parts of the bivalve shell (Plate 3, c.) ; when the valves are closed, the line where they meet is called the seam. ”

“ Here we find the scorpion, with seven digitations, from India; the spider, with the same number, a large and fine shell, also from India.
"Strombus has a short canal, the right-margin dilated with age into a simple wing, having, at the lower part, a sinus, separated from the canal at the base of the shell.
"All the species are natives of hot climates; some attain a very large size, such as S. gigas, so frequently seen in shops, and as ornaments in a room. ”

“ The operculum is either horny, like that of the periwincle, or of a harder substance, like the shell itself.
"The umbilicus is a circular hole in the body of the shell. This perforation produces a very curious effect when it is very large. When the umbilicus is wanting, the shell is called imperforate.
"If the spire is truncated, it is decollated; if it is surrounded with spires, it is coronated, or crowned.
"Second section, without a regular spire. The teeth in univalve shells, as the cowry, are ridges upon the aperture. ”

“ From the well-known genus Turbo, a new one has been formed, called Litorina, which includes all the shells of our own coasts that formerly ranked under Turbo. Consequently we find the periwincle has changed its generic name, and from Turbo it is altered into Litorina. ”

“ An ancient writer asserts that the Pinna is attended by a crab, that finds a habitation in its shell, and repays the favour by giving notice, by a gentle nip, when a fish comes within reach; the Pinna opens the valves of the shell, and secures the prey, which serves for the food of both. ”

“ O. volva, the weaver's-shuttle, is a rare and highly-valued species. It is nearly globular in the middle, and is terminated at each extremity by a long beak: it comes from the West Indies. O. gibbosa is a common species; the shape is oblong, with a ridge in the centre. ”

“ The shells of the genus Cypræa, cowry, are general favourites: the species are fifty-eight; one British, C. pediculus. C. moneta (Plate 1) is very common. The generic characters are, shell univalve, involute, obtuse, smooth; aperture linear, the whole length of the shell ”

“ C. elegans is « 70 » often to be found on hedge-banks or chalk soils. It is a pretty shell, sometimes white, often tinted with purple.
"In the family Lymænana, the species are amphibious; inhabiting fresh-water; but rising to the surface to breathe the air. They have but two tentacula.
"As several species are British, you may have the satisfaction of examining them for yourselves.
PLANORBIS.
"The genera are,
"Planorbis is a discoid shell, and one peculiarity of the genus is, that they are all reverse shells. ”

“ Linnæus made two divisions; later writers have separated them into several distinct genera, which will be noticed when we attend to Lamarck's system. The species are forty-five, of which several are found on the British shores, as L. tulipa, L. diadema, L. tintinnabulum, L. balanus, L. anatifera, &c. The Indian, American, and Atlantic oceans afford numerous species.
PHOLAS.
"Third genus, Pholas. Generic character: shell bivalve, gaping or divaricated, with several smaller hinges situated upon the hinge; hinge recurved, with an incurved tooth." ”

“ The families in this order are numerous: they are divided into two sections; the first includes those that breathe only in the air; the second those that can exist only in the water, and are furnished with a syphon. ”

“ Elliot, "contains all the bivalves of Linnæus, and some genera taken from the univalves and multivalves.
"The animals of this class are shell-bearers or carriers, they remain constantly fixed in their habitations: the body is fastened to the shell by one or two strong muscles: when the shell is vacant we find the cicatrix. ”