A Conchological Manual, George Brettingham Sowerby [little readers .TXT] 📗

Barbadensis,

   _Lam._ No. 49. p. 78. Fêr. Moll. pl. 47, 2, 3, 4."

 

   LUCINA. Brug. _Fam._ Nymphacea, Lam. Conchacea, Bl.--_Descr._

   Equivalve, inequilateral, orbicular, lenticular, radiately striated;

   hinge with, generally, two minute cardinal teeth, which are sometimes

   nearly obsolete, and two lateral teeth, on each side of the umbo in one

   valve, one in the other; ligament external, partly hidden by the

   margins of the valves when closed. Muscular impressions two in each

   valve, the anterior one produced into an elongated, ligulate band, the

   posterior short and semi-rotund; impression of the mantle not

   sinuated.--_Obs._ The shells of this genus resemble Amphidesma in

   general form, but are distinguished by the external ligament, the

   elongated muscular impression, and the want of a sinus in the palleal

   impression. East and West Indies, and European shores. Fig. 104, L.

   Tigerina.

 

   LUNULATE. (_Luna_, the moon, dim.) Moon-shaped, having the form of a

   crescent. Applied most frequently to muscular impressions. Semilunar is

   sometimes used, perhaps with greater accuracy, to express the same

   shape.

 

   LUNULE. An impression on the anterior dorsal margin of some bivalve

   shells. The similar impression on the posterior dorsal margin is called

   the _escutcheon_.

 

   LUPONIA. Gray. A genus composed of species of CYPRÆA, Auct. which are

   described as having the anterior of the columellar lip crossed by

   several irregular ridges, without any distinct marginal ones,

   internally narrow, flat; the shell pear-shaped, smooth, or

   cross-ribbed. _Ex._ C. Algoensis, Luponia Algoensis, Gray, fig. 447.

 

   LUTRARIA. Auct. (_Lutum?_ mud.)--_Fam._ Mactracea, Lam.--_Descr._ Thin,

   equivalve, inequilateral, transverse, oblong or ovate, gaping at both

   extremities; hinge with one double and sometimes one single cardinal

   tooth in each valve, and a triangular, oblique pit with a prominent

   margin, containing the ligament; muscular impressions distant; palleal

   impression having a large sinus.--_Obs._ This genus differs from Mactra

   in the entire absence or indistinctness of lateral teeth. Fig. 77, L.

   Papyracea. (Ligula, Leach.) Fig. 78. L. Solenoides. Sandy and muddy

   shores.

 

   LUTRICOLA. Bl. LUTRARIA. Lam. Fig. 77, 78.

 

   LYCOPHRIS. Montf. A microscopic fossil described as resembling

   NUMMULITES, but having a granulated surface.

 

   LYMNADEA. Sw. A sub-genus of "Mysca," Turton, in the family of Nayades,

   Lam. thus described: "Posterior hinge margin elevated and winged; the

   valves connate; the surface smooth. L. alata. _Sw._ _Ex._ Conch. (fig.

   48.) fragilis. _Sw._ Zool. Ill. compressa, _Lea._ Am. Tr. iii. pl. 12.

22." Sw. p. 379.

 

   LYMNEA. See LIMNEA.

 

   LYMNEUS. Lam. See LIMNEANA.

 

   LYONSIA. Turt. Inequivalve species of ANATINA, Auct. which have no

   spoon-shaped cavity in the hinge, but an accessary piece. L. striata,

   fig. 491, 2.

 

   LYRODON. Goldf. TRIGONIA?

 

   MACLURITES. Lesuour. Journ. des Scienc. Nat. Philad. t. 1. p. 312. pl.

fig. 2, 3.

 

   MACOMA. Leach. VENUS tenuis, Bl. and similar species, described as

   "Clothed with an epidermis; striated, compressed, oval; the summits not

   very prominent; two bifid teeth upon the right valve and a single

   undivided one upon the left."

 

   MACRODITUS. Montf. LENTICULINA, Bl. A genus of microscopic

   Foraminifera.

 

   MACROSPIRA. Guild. A genus composed of HELIX octona, Auct. Macrospira

   aperta, Guild.

 

   MACROSTOMATA. Lam. ([Greek: Makros], _macros_, long; [Greek: stoma],

   _stoma_, mouth.) A family belonging to the first section of the order

   Trachelipoda, the shells belonging to which are described as haliotoid

   or ear shaped, with a very large aperture, destitute of an operculum.

   This family contains the following genera, which maybe thus

   distinguished.

 

VELUTINA. Globose, with velvety epidermis. Fig. 337.

 

STOMATIA. Ear-shaped; pearly within; including STOMATELLA. Fig.

       335, 336.

 

SIGARETUS. The same, not pearly; including _Cryptostoma_. Fig.

       334.

 

CORIOCELLA. The same, thin, transparent.

 

HALIOTIS. The same, not thin, nor transparent; with holes;

       including _Padollus_. Fig. 338, 339.

 

SCISSURELLA. Heliciform, with a slit near the aperture. Fig.

       340.

 

PLEUROTOMARIA. Trochiform, with a slit at the edge of the

       aperture. Fig. 341.

 

   MACTRA. Auct. (_Mactra_, a kneading trough.) _Fam._ Mactracea, Lam.

   Conchacea, Bl.--_Descr._ Usually thin, equivalve, sub-equilateral,

   sub-trigonal, slightly gaping at the extremities; hinge with one

   cardinal tooth, divided into two parts, diverging from the umbo, with

   sometimes a very small laminar tooth close to its side; a deep

   triangular pit near the centre, containing the cartilage; one long,

   lateral tooth on each side of the umbo in one valve, received between

   two in the other; muscular impressions two, lateral; palleal impression

   with a small sinus.--_Obs._ This genus contains many species of

   beautiful shells found in various parts of the world, some are common

   in Britain. Fossil species are not numerous, they occur in the tertiary

   strata. Fig. 79 to 82.

 

   MACTRACEA. Lam. A family of the order Conchifera Dimyaria, Lam. Sect.

   Tenuipedes. The cartilage placed in a trigonal pit with a small

   external ligament. The genera may be thus distinguished.

 

LUTRARIA. No lateral teeth, shell gaping. The short species

       constitute the genus _Ligula_. Fig. 77, 78.

 

MACTRA. Lateral teeth, shell closed. This genus has been divided

       into Mactra, Mulinia, Schizodesma and Spisula, by Mr. Gray. Fig. 79

       to 82.

 

GNATHODON. Teeth serrated, thick, one angular. Fig. 83.

 

CRASSATELLA. Shell thick, lateral teeth. Fig. 84.

 

AMPHIDESMA. A distinct external ligament, internal ligament

       oblique. Fig. 85.

 

ERYCINA. A short tooth on each side of the cartilaginous pit in

       each valve. Including Mesodesma. Fig. 86.

 

UNGULINA. Ligament flat, divided. Fig. 88.

 

   MACULATED. (From _Macula_, a spot.) Spotted or patched. This term is

   applied by conchological writers, to those shells which are coloured in

   spots or small patches. In the same sense it is also used as a specific

   name. As for instance, Cytherea maculata, fig. 167, c. and Hippopus

   maculatus, fig. 156.

 

   MAGAS. Sow. ([Greek: Magas], _magas_, a board, a deck.) _Fam._

   Brachiopoda, Lam.--_Descr._ Equilateral, inequivalve; one valve convex,

   with a triangular area, divided by an angular sinus in the centre; the

   other valve flat, with a straight hinge line and two small projections;

   a partial longitudinal septum, with appendages attached to the hinge

   within. Differing from Terebratula in having a triangular disc, and not

   a circular perforation. Magas pumilus, fig. 299. Fossil in chalk.

 

   MAGILUS. Montf. _Fam._ Cricostomata, Bl. Serpulacea, Lam.--_Descr._

   Thick, tubular, irregular, contorted; rounded above, keeled beneath,

   free; apicial extremity convolute, heliciform, ovate or sub-globose;

   aperture elliptical.--_Obs._ This shell when in a young state presents

   the characteristics of a regularly formed spiral univalve, living in

   holes in madrepores. As the madrepore increases in bulk, the animal

   gives an eccentric course to the shell, in order to have its aperture

   even with the surface, and leaving the nucleus or young shell behind,

   fills it up with calcareous matter to reside in the open extremity of

   the tube. Fig. 9, 10. Red Sea and Mauritius.

 

   MALACOTA. Schum. OTION. Leach.

 

   MALACOZOA. Bl. ([Greek: Malakos], _malacos_, soft; [Greek: Zôon],

   _zoon_, animal.) The type or general appellative in De Blainville's

   system, including all molluscous animals, excepting those with

   multivalve shells.

 

   MALDANIA. Lam. The second family of the order Annelides Sedentaria. The

   only genus of shells described in this family is Dentalium, fig. 2, to

   which may be added Pharetrium, König. fig. 3. It is doubtful however

   whether the latter do not belong to an unknown genus of Pteropodous

   Mollusca.

 

   MALEA. Valenciennes. A genus composed of DOLIUM latilabrum, Kiener, and

   other similar species.

 

   MALENTOZOA. Bl. ([Greek: Malakos], _malacos_, soft; [Greek: en], _in_,

   [Greek: temnô], _temno_, cut; [Greek: Zôon], _zoon_, animal.) Or

   articulated mollusca. The sub-type in De Blainville's system,

   comprehending those with multivalve shells.

 

   MALLEACEA. Lam. A family belonging to the order of Conchifera

   Monomyaria. Containing the following genera of irregular pearly

   bivalves.

 

AVICULA. Hinge linear, simple, including _Meleagrina_. Fig. 163,

       164.

 

PERNA. Hinge with linear grooves, including _Pulvinites_. Fig.

       166, 170.

 

GERVILLIA. Shaped like Modiola, with irregular grooves. Fig.

       162.

 

CRENATULA. Hinge with a series of pits. Fig. 168.

 

CATILLUS. Like Perna, but more regular and convex. Fig. 167.

 

MALLEUS. A triangular disc on the hinge, and two auricles. Fig.

       165.

 

   MALLEUS. Auct. (_Malleus_, a hammer.) _Fam._ Malleacea, Lam.

   Margaritacea, Bl.--_Descr._ Equivalve, inequilateral, foliaceous,

   trilobate, undulated, irregular, attached by a byssus passing through a

   sinus in one valve; hinge rectilinear, lengthened by two auricles; with

   a small disc under the umbones, containing the ligament, and a groove

   containing the cartilage; muscular impressions one in each valve,

   large, uniform, and one or two others extremely minute.--_Obs._ Malleus

   Vulgaris, the type of this genus, is a most singular shell, commonly

   called the "Hammer Oyster," from the peculiarity of its shape. It

   belongs to the Linnæan genus Ostrea, from which it differs in being

   attached by a byssus. Fig. 165, M. Vulgaris. Tropical.

 

   MAMILLARIA. Sw. A sub-genus of NATICA, corresponding with Polinices of

   Montfort, having the spire small and the umbilicus filled. _Ex._ Natica

   Mamilla, Auct. fig. 327.

 

   MAMMILLATED. (_Mammula_, a little teat.) A term applied to the apex of

   a shell when it is rounded like a teat. _Ex._ Voluta Vespertilio, fig.

   433.

 

   MARGARITA. Leach. (_Margarita_, a pearl.) A genus of small shells

   resembling the genus Trochus, from which it differs in having an

   operculum consisting of few whorls. M. tæniata, fig. 362. Mr. G. B.

   Sowerby, sen. has enumerated 15 species in a list accompanying the

   figures published by the author of this manual in Nos. 132 to 134 of

   his Conchological Illustrations.

 

   MARGARITACEA. Bl. The third family of Lamellibranchiata, Bl. The shells

   belonging to it are described as irregular, inequivalve, inequilateral,

   black or horny without, pearly within; hinge auriculated, scarcely

   developed, and without teeth. The ligament is variable and there is a

   large sub-central muscular impression. This family contains the genera

   Vulsella, Malleus, Pinna, Crenatula, Inoceramus, Catillus, Pulvinites,

   Gervillia and Avicula.

 

   MARGARITACEOUS. (_Margarita_, a pearl.) Pearly.

 

   MARGARITANA. Schum. A sub-genus of Uniones, composed of species having

   "one cardinal tooth." ALASMODON, Say. MYA Margaritifera, Linn.

 

   MARGARITIFEROUS. (_Margarita_, pearl; _fero_, to bear.) Pearl-bearing.

   Applied to shells which form pearls; as Meleagrina Margaritifera, or

   Pearl-bearing Oyster.

 

   MARGINAL. Near the margin or edge.

 

   MARGINATED. (_Margo_, edge.) Having an edge or border thicker than the

   rest of the shell, from which circumstance the little genus Marginella

   derives its name.

 

   MARGINELLA. (A little rim or border.) _Fam._ Columellaria, Lam.

   Angyostomata, Bl.--_Descr._ Ovate, smooth, shining, with a short,

   sometimes hidden spire; aperture narrow, emarginated; columella with

   several oblique folds; outer lip neatly reflected.--_Obs._ This genus

   of pretty little shells differs from Voluta, in the reflection of the

   outer lip. The animal covers the greater part of the shell with the

   mantle, and by continually depositing vitreous matter gives it a bright

   polish, which, together with the delicately neat arrangement of colours

   in most species, renders them exceedingly beautiful. The Marginellæ are

   marine and tropical. A few fossil species are found in the

   Calc-grossier. Fig. 437. M. Glabella. GLABELLA, Sw.

 

   MARGINULINA. D'Orb. A genus of microscopic Foraminifera.

 

   MARINE CONCHACEA. See CONCHACEA.

 

   MARINE TESTACEA. Those shell-fish which inhabit seas, lakes, &c. of

   salt water, in distinction from the _Aquatic_ Testacea, or those which

   are found in rivers, ponds or stagnant pools of fresh water: and also

   from the _Land_ Testacea, which live on land and breathe air. The great

   proportion of shells belong to the former class, those of the latter

   two classes being limited in their number, and in the genera to which

   they belong.

 

   MARINULA. King. A genus of small shells resembling Auricula and

   Pedipes, described as "Ovate, sub-solid, with aperture ovate entire;

   columella bidentate, uniplicated towards the base, with large

   sub-remote teeth; the largest uppermost; no operculum."

 

   MARMAROSTOMA. Sw. A genus of "Trochidæ," Sw. thus described: "Umbilicus

   deep; spire of few whorls, much depressed, and obtuse; inner lip

   obsolete; base even more produced than in _Senectus_, but never

   distinctly channeled. M. versicolor. Mont. 176. f. 1740, 1741,

   undulata. Chem. 169. f. 1640, 1641," Sw. p. 348.

 

   MARPESSA. Gray. A sub-genus of Clausilia, C. bidens, &c. Auct. Gray's

   Turton, p. 212.

 

   MARTESIA. Leach. A genus composed of those species of PHOLAS, Auct.

   which are described as short, cuneiform, nearly closed at both

   extremities, having several accessary pieces on the middle of the back,

   and two marginal, lower down.

 

   MEASUREMENT. The most approved method of stating the measurements of

   various kinds of shells is as follows: _symmetrical convolute

   univalves_, the length is from anterior to posterior; the depth from

   ventral to dorsal; the breadth, from side to side of the aperture. Of

   _symmetrical conical univalves_, length, from front to back; breadth

   from side to side; depth from apex to base. Of _spiral univalves_,