Thomas Brown

“ Genus Bulimus. Pl. X. Animals of this genus in formation are precisely as the Helix; they are, however, oviparous, producing eggs with the shell containing the animal perfectly matured; they are frequently as large as a pigeon’s egg.
Shell. Oval, sometimes turriculated, oblong; the summit of the spire obtuse, and the last whorl larger than all the others together; aperture oblong, oval, edge disunited; in adults the lip much reflected; columella smooth, with an inflection in the middle, the base entire, not channeled. Inhabits mountainous situations in Europe and America ”

“ In various genera it extends the whole length of the shell, as in the Cypræa, and some of the Cones with depressed spires. This in several individuals is either entirely open, or is closed by an operculum or lid, which is usually affixed to the foot of the animal.
Canal, or gutter, is the inside of the elongations of the aperture, or both lips of the shell of those species with a beak, in which it forms a concave channel or gutter, running from its commencement in the aperture to the extremity or base. ”

“ No attention has been given to the mere History of the subject; it is conceived that any disquisition on this head would more properly appertain to works of ultimate research, than to one whose sole intention is to make the pupil acquainted, in as tangible a form as possible, with results. To afford, at a cheap rate, a concise, yet sufficiently comprehensive, and especially a well illustrated school-book, has been the principal design. ”

“ Byssus, or beard, is an appendage composed of filaments of a silky texture, by which some of the Bivalves fasten themselves to their beds, such as the Mytilus, Pinnæ, &c. Plate II. fig. 6, s.
UNIVALVE. The shells called univalve, or those composed of one part only, are far more numerous than the two preceding, both in genera and species; and it requires a considerable degree of attention to discriminate many of the species, as they run into each other so much; and they are divested of the strong and distinct character afforded by the teeth of bivalves ”

“ 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. ”

“ In the Testacea, on the contrary, the inhabitant is of a simple and soft texture, without bones, and is attached to its domicil by a certain adhesive muscular force; this domicil, too, is a permanent one, and is increased, from time to time, by gradual additions on the part of the tenant; while the entire shell, which is distributed in layers, or strata, is a combination of carbonate of lime, with a very small portion of gelatinous matter. Such animals, then, with such shells, form, alone, the subject of a proper “Conchology.” ”

“ Body oval, spiral above, enveloped in a mantle of which the right edge is furnished with lobes; foot oval and somewhat short; eyes situated at the external base of long, conical, retractile tentacula; mouth having a long extensible proboscis armed with hooked teeth; organs of respiration formed by two unequal branchiæ.
Shell. Fusiform, a little wrinkled, with a turriculated spire; a small oval aperture, terminated by a straight canal more or less long, with the right edge trenchant; a horny operculum. Distinguished from the Cerithium by having a notch in the margin. Twenty-nine living species. ”

“ This division comprehends not only the Mollusca, but also the Testacea of Aristotle and of Pliny, and, of course, had reference to molluscous animals in general—of which the greater portion have shells.
A treatise concerning the shells, exclusively, of this greater portion, is termed, in accordance with general usage, a Treatise upon Conchology or Conchyliology; although the word is somewhat improperly applied, as the Greek conchylion, from which it is derived, embraces in its signification both the animal and shell. Ostracology would have been more definite. ”

“ Shell. Usually very thick, nacred within, covered with epidermis, corroded at the summits, which are dorsal and subanterior; dorsal hinge formed by a double precardinal tooth, more or less compressed, irregularly dentated on the left valve, and simple on the right, together with a long lamellous tooth under the ligament: ligament external, dorsal, and postapicial; two muscular impressions, well marked, besides those of the retractile muscles. The species of this genus grow more numerous daily; they are found in all countries, but particularly in North America. ”

“ Siphunculus is that small round perforation which forms a communication between the chambers of the Spirulæ, and penetrates through the whole spire of the shell. Plate III. fig. 11, v.
Varices are transverse ribs which cross the whorls of shells in some species of Buccinum, Murex, and Tritonia, and exemplified in the Cassidaria. Varices are formed by the periodical growth of the shells, these being the margin of the outer lip, to which the animal has attached its periodical enlargements. In some species they have more the form of sutures than ribs ”

“ Shell. Marine, found in almost all parts of the world, some smooth, others knotted, spined, tuberculated, or undulated; thick, generally pearly, spire sometimes depressed, at others elevated and pointed at the summit, sharp or carinated at its circumference, frequently umbilicated, not always; aperture transversely depressed, the margins not united at the upper part; columella arched and twisted, often projecting forward; operculum horny, thin, with numerous spiral whorls, increasing from the centre to the circumference. Inhabits the European seas. Ninety-nine living species. ”

“ In fixed shells, such as Serpulæ, there is no difficulty, as the side which is sessile must be considered as the base or under part. Thus, in the Serpula Lucida the fixed part is sometimes very small, and the mouth turns spirally upwards, in a contrary direction to the sun; and therefore must be considered a reversed or heterostrophe shell, the same as if the volutions nearest the mouth had turned laterally upon the centre or fixed ones. ”

“ Body round and terminated posteriorly by a tendinous or muscular filament, attaching itself to the syphon, by which the partitions of the shell are pierced; the mantle opening obliquely, and prolonged into a sort of hood above the head (which is provided with digitated tentacula) , and surrounding the aperture of the mouth. ”

“ Shell. Somewhat diversiform, but most usually elongated and more or less oblique at the posterior extremity, often very inequilateral; summits more or less distant and little flexed to the front; hinge anomalous, straight, or a little flexed, long, and formed by a line of short vertical teeth, decreasing from the extremities to the centre; ligament exterior, wide, nearly as much before as behind the summit; two muscular impressions united by a band or palleal impression, not very distinct. Inhabits the American and British seas. Forty-one living species. ”

“ XI. Animal. Spiral; foot fringed anteriorly by a transversely wrinkled band; tentacula long, very fine towards their extremity, somewhat thick at their base, and having the eyes upon an inflation; the head skirted with a veil or fringe garnished with filaments.
Shell. Turreted, not nacred, rather thin, striated in the direction of the decurrence of the spire; very pointed, and with numerous whorls; aperture rounded; the edges posteriorly, the right exceedingly thin, and slightly sinuous towards the middle; operculum horny. Inhabits the Indian and American Oceans. Twenty-one living species. ”

“ Genus Saxicava. Pl. VI. Animal. Long, subcylindrical, the mantle closed in all parts, prolonged behind by two long tubes, thick and close together externally, pierced interiorly and in front with a round orifice, for the passage of a very small foot; mouth very large; labial appendages small; branchial laminæ free, the external pair much shorter than the internal.
Lamarck has thought proper to remove this genus from the Mytilus; it possesses the faculty, like the Pholas, of penetrating rocks and substances, and cannot be extracted but by breaking the substance in which it is imbedded. ”

“ Of a somewhat variable form, generally striated longitudinally and much compressed, equivalved, more or less inequilateral; the anterior side almost always longer and more rounded 50than the posterior, which constantly presents a flexuous fold, at least at its inferior edge; summits feebly marked; hinge similar; one or two cardinal teeth; two lateral teeth, far apart with a pit at their base in each valve; ligament posterior, large; round muscular impressions. The finest species of this beautiful shell are found in the pearl fisheries of Ceylon; and numerous species on the American shore. ”

“ Shell. Solid, equivalve, regular, inequilateral; summits equal, reflexed, and slightly projecting; four primary teeth on one valve, of which three are divergent, and approximating at the base, and one remote—this circumstance easily distinguishing it from the Venus. On the other valve are three primary divergent teeth with a distant cavity parallel with the edge. Inhabits the British, Mediterranean, and American seas. Eighty-three living species. ”

“ Four genera. 1. Genus Solen. Pl. VI. Animal. Body cylindroid, much elongated; the mantle in form of a canal open at both ends, closed in the rest of its extent by a thick epidermis which surrounds it; a cylindroid anterior foot.
Shell. Equivalve, extremely inequilateral, the summits very small, and entirely at the commencement of the dorsal line; one or two teeth in the hinge. Inhabits the seas of America and Europe. Twenty-one species. ”

“ General sinistral, oval, oblong, or globular, very smooth, spire prominent, aperture oval, contracted posteriorly, right edge sharp, columella twisting obliquely, and enlarging to join itself to the anterior part of the margin, the whorls turning to the left hand gives this shell the appellation of heterostrophe. Inhabits the ditches of America and Europe. Ten species. ”

“ Genus Crepidula. Pl. X. Animal. Head anteriorly forked, having two conical tentacula, with the eyes placed at their exterior base; mouth simple, destitute of jaws, and situated in the bifurcation of the head; branchiæ with tufts and projecting from the branchial cavity; the mantle never bordering the shell; foot minute, orifice lateral.
Shell. Ovate, or oblong; the back almost always convex, concave beneath; the spire very much inclined towards the margin; the aperture partly closed by a horizontal lamina. Inhabits the American seas. Thirteen species. ”

“ The common works upon this subject, however, will appear to every person of science very essentially defective, inasmuch as the relation of the animal and shell, with their dependence upon each other, is a radically important consideration in the examination of either. ”

“ Shell. Marine; many of them very rare and valuable; their beauty of colouring disposed so as to resemble the plumage of a pheasant. Oval, rather thick, smooth and glossy, spire pointed; columella uniting itself with the left edge, forming interiorly a longitudinal callosity; aperture oval, larger before, with edges disunited; operculum calcareous, oval, oblong, subspiral, the summit at one extremity. Inhabits the British coast. Twelve species. ”

“ Shell. Irregular, inequivalve, inequilateral, roughly foliaceous, the left or inferior valve adhering, larger and deeper than the other, its summit prolonged with age into a sort of heel; the right or superior valve more or less operculiform; hinge oral, toothless; ligament subinterior, short, inserted in an oblong cardinal cavity increasing with the summit; muscular impression single and subcentral. Found in all seas near the mouths of rivers. Defrance enumerates one hundred and twenty species. Lamarck thirty-three fossil, forty-nine living. ”