A Conchological Manual by George Brettingham Sowerby (early reader books .txt) 📖
- Author: George Brettingham Sowerby
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breadth, across from the outer lip to the opposite side. Of
_non-symmetrical bivalves_, the length is from the anterior to the
posterior margin; breadth, from the greatest convexity of one valve to
the corresponding part of the other; depth, from the ventral to the
dorsal margin.
MEGADESMA. Bowd. ([Greek: Megas], _megas_, great; [Greek: desma],
_desma_, ligament.) POTAMOPHILA, Sow. GALATHÆA, Lam.
MEGADOMUS. Sw. A sub-genus of Unio, thus described: "Only one lateral
tooth in each valve; cardinal teeth two; posterior hinge margin winged.
gigas, _Sw._" Sw. p. 378.
MEGALODON. Sow. ([Greek: Megas], _megas_, great; [Greek: odos], _odos_,
tooth.) _Fam._ Cardiacea, Lam.--_Descr._ Equivalve, longitudinal,
acuminated at the umbones, thick; hinge forming an incrassated septum
across the cavity of the shell, with a large bifid tooth in the right
valve, and one irregular and one pointed in the left; ligament long,
external.--_Obs._ The general form, the thickened hinge reaching across
the cavity of the valve and the terminal umbones serve to distinguish
this genus from Cardita, to which, however, it is nearly allied. M.
cucullatus, fig. 127.
MEGALOMASTOMA. Guild. A sub-genus of Cyclostoma, thus described:
"Cylindrical, resembling _Pupa_, but has a horny operculum; spire not
thickened; teeth or fold on the pillar none, flavula _Sw._ En. Méth.
f. 6, brunnea _Guild._ (_fig. 97. g. h. 1._)" Sw. p. 336. Mr. Grayapplies the name to those species which have "a groove or ridge in
front of the mouth near the pillar."
MEGARIMA. Rafinesque. A genus proposed to include species of
TEREBRATULA, Auct. which are smooth and nearly equivalve. T. lævis, T.
crassa, T. truncula.
MEGASPIRA. Lea. ([Greek: Megas], _megas_, great, and spire.) M.
Ruschenbergiana, (fig. 294) is a pupiform land shell remarkable for the
length of its spire, which consists of no less than twenty-five close
set, narrow, gradually increasing whorls. The outer lip is simple,
slightly thickened; the inner lip has a tooth on the body-whorl, and
two folds on the columella. Only one species of this singular shell is
known.
MEGATREMA. Leach. A genus composed of those species of Pyrgoma, Auct.
which have a large aperture. Fig. 33.
MELACANTHA. Sw. A sub-genus of Melania. Sw. p. 341.
MELAFUSUS. Sw. A sub-genus of Melanopsis. Sw. p. 341.
MELAMPUS. Montf. CONOVULUM, Lam. A genus composed of species of
AURICULA, Auct. of a conical form. A. conoidalis, fig. 298.
MELANIA. Auct. ([Greek: Melas], _melas_, black.) _Fam._ Melaniens, Lam.
Ellipsostomata, Bl.--_Descr._ Turrited; spire generally elongated,
acute; aperture entire, oval or oblong, pointed at the posterior
extremity, rounded anteriorly, with a kind of indistinct canal or
sinuosity: epidermis thick, generally black.--_Obs._ In common with
other fresh-water shells, the Melaniæ are frequently found with
corroded apices. This genus is known from Melanopsis by the absence of
the notch at the anterior part of the aperture. The Melaniæ occur in
rivers of warm climates. The fossil species are frequent in upper
marine formations. Fig. 313, M. subulata.
MELANIANA. Lam. (Melaniens.) A family belonging to the first section of
the order Trachelipoda. The genera contained in it maybe distinguished
as follows.
MELANOPSIS. Aperture notched; columellar lip thickened above;
including _Pirena_. Fig. 315, 316.
MELANIA. Aperture not notched; columellar lip not thickened;
including _Auculosa_, _Pasithæa_, _Io_. Fig. 313, 314, 317.
MELANITHES. Sw. A sub-genus of Melanopsis. Sw. p. 341.
MELANOIDES. Olivier. MELANOPSIS. Fer.
MELANOPSIS. Fer. _Fam._ Melaniana, Lam. Entomostomata, Bl.--_Descr._
Oval or oblong, fusiform; spire acute, sometimes elongated; aperture
oblong or oval, pyriform, with a distinct notch at the anterior
extremity; columella tortuous, callous, thickened at the extremity near
the spire; epidermis thick, horny, generally black.
Subtropical.--_Obs._ This description includes the two first species of
the genus Pirena, Lam. The Melanopsides are known from the Melaniæ by
the notch in the aperture. Fig. 315. M. costata.
MELAS. Montf. MELANIA, Auct.
MELATOMA. Sw. A sub-genus of Melanopsis. Sw. p. 341.
MELEAGRINA. Lam. MARGARITA. A genus composed of the Pearl Oyster and
similar species, separated from Avicula on account of the roundness of
their general form, but re-united by Sowerby. For generic characters,
see Avicula. Fig. 164. M. margaritifera.
MELEAGRIS. Montf. TURBO Pica, Auct. and similar species, having the
aperture oblique, the columella gliding imperceptibly into the outer
lip, and having an umbilicus.
MELINA. Schum. PERNA, Auct.
MELO. Brod. (_Melo_, a melon.) _Fam._ Columellaria, Lam.--_Descr._
Light, ventricose, oval, with a light greenish brown epidermis, spire
short, papillary, regular, sometimes hidden by the last whorl; aperture
large, nearly as long as the whole shell, emarginated anteriorly; outer
lip thin; columella slightly curved, with four or five laminar,
oblique, prominent plaits.--_Obs._ The genus Melo has been separated
from _Voluta_ principally on account of the largeness of the aperture,
the lightness of the shell and the thinness of the outer lip. Melo
differs from Cymba in the regularity of the spiral apex, and in the
greater rotundity of the shell. The Melons are beautifully coloured
large shells, found in the seas of the old world. The Melo Indicus has
a certain resemblance to a Melon. Fig. 435. M. Æthiopicus.
MELONIA or MELONITES. A genus of microscopic Foraminifera.
MERCENARIA. Schum. VENUS Mercenaria, Auct. The Money shell which passes
current for cash, under the name "Wampum," among the North American
Indians.
MERETRIX. Lam. Original name for Cytherea, Lam.
MEROE. Schum. CYTHEREA Meroe, sulcata, scripta, hians, Auct. and
similar species. Fig. 117, a.
MESODESMA. Desh. ERYCINA, Lam. according to G. B. Sowerby.
MESOMPHYX. Rafinesque. A genus proposed to be separated from HELIX,
Auct.
MICROTOMA. Sw. A genus of "Purpurinæ," Sw. thus described, "Pillar very
broad and curving inwards; aperture effuse; the notch at the base small
and nearly obsolete; spire very short, patula. Mart. 69. f. 758, 759.
persica. En. Méth. 397. f. 1. unicolor. _Sw._ Chem. f. 1449. Sw. p.
301." Purpura Persica. Fig. 414.
MILIOLA. Lam. A genus of microscopic Foraminifera.
MISILUS. Montf. A genus of microscopic Foraminifera.
MITRA. Lam. (_Mitre._) _Fam._ Columellaria, Lam. Angyostomata;
Bl.--_Descr._ Oblong, thick, covered with a light brown epidermis;
spire long, turrited, acute; aperture emarginated anteriorly; outer lip
thickened; columella with several oblique, thick plaits.--_Obs._ The
pretty small shells composing this genus differ from Marginella, not
only in general form, but in the outer lip not being reflected. Some
species of Voluta, of a more elongated shape than the rest, present a
near approach to the most ventricose of the Mitræ. The apex of Mitra,
however, is always acute, while that of Voluta is generally papillary.
The aperture of the former is narrow and the inner lip thickened, the
contrary being the case with the latter. The shells of this genus are
varied in colouring which is generally rich; and also in form, some
being angulated, some plicated, some coronated and others smooth. The
species are mostly tropical; very few occur so far north as the
Mediterranean. Fossil species are numerous in the Eocene beds. Fig.
M. Plicaria. Fig. 432. Conohelix marmorata, Sw.
MITRELLA. Sw. A genus consisting of MITRA Fissurella, casta,
Olivæformis, and similar species, described as "Rather small;
olive-shaped; unequally fusiform; always smooth and polished, and
sometimes covered with an epidermis; base obtuse and effuse; spire
nearly or quite equal to the aperture; plaits of the pillar few,
oblique, and extending beyond the aperture, which is smooth
internally." Sw. p. 321. M. Fissurata, E. M. 371. f. 1. Olivarii, f. 2.
Dactylus. 372. f. 5. _Ex._ Mitra bicolor.
MITREOLA. Sw. A genus of "Mitranæ," Sw. thus described: "Small;
unequally fusiform; the base obtuse; inner lip, typically thickened,
inflected, and either toothed or tuberculated; plaits on the pillar
distinct, the inferior largest; tip of the spire sometimes papillary;
aperture without either striæ or groove." Sw. p. 320, M. Monodonta, M.
Terebellum. Zool. Illustr. II. 128. f. 1. f. 2.
MODIOLA. Lam. (_Modiola_, a little measure.) _Fam._ Mytilacea,
Lam.--_Descr._ Equivalve oblique, cuneiform, inequilateral, thin, with
the anterior side short and narrow, slightly gaping to admit the
passage of a byssus, and the posterior side elongated, broad,
sub-quadrate; hinge thin, toothless, rectilinear, with a long, partly
external ligament; muscular impressions two in each valve; palleal
impression irregular, not sinuated.--_Obs._ This genus differs from
Mytilus, to which the common muscle belongs, in the anterior margin
being rounded out beyond the umbo, which in Mytilus is terminal. The
Lithodomi may be known from this genus by their cylindrical form. Fig.
160, M. Tulipa.
MOLLUSCA. (From _Mollis_, soft.) The twelfth class of invertebrated
animals with univalve shells or none; divided into the following
orders: Pteropoda, Gasteropoda, Trachelipoda, Cephalopoda, Heteropoda,
fig. 220 to 488. The term mollusca is also used in a general sense to
include the classes Conchifera and Mollusca of Lamarck, corresponding
with the type Malacozoa of De Blainville.
MONEY COWRY. Cypræa Moneta, which passes current in some parts of
Africa and the East Indies.
MONILEA. Sw. A sub-genus of Monodonta. Sw. p. 352.
MONOCEROS. ([Greek: Monos], _monos_, single; [Greek: Keras], _ceras_,
horn.) _Fam._ Purpurifera, Lam.--_Descr._ Ovate, thick, covered with a
brown epidermis; spire short, consisting of few whorls; aperture
emarginated anteriorly; columella rather flat; outer lip thick, with a
prominent tooth near the extremity.--_Obs._ This genus resembles
Purpura, in every respect, except in having the tooth from which the
name is derived. A catalogue of 16 species by Mr. Sowerby, sen. is
published with figures of 14, in parts 58 to 67 of the Conchological
Illustrations by the author. The species belong to the South American
coasts of the Pacific Ocean.
MONOCONDYLÆA. D'Orb. A sub-genus of Uniones, described as equivalve,
inequilateral, sub-rotund or angulated; hinge consisting of a large,
obtuse, round cardinal tooth in each valve, with no lateral teeth.
Monocondylæ (Unio) Paraguayana, D'Orb. fig. 149.
MONODONTA. Lam. ODONTIS, Sow. A genus separated from Trochus, Auct. on
account of the tooth or notch with which the columella abruptly
terminates. M. labeo, fig. 366.
MONOICA. Bl. The second sub-class of the class Paracephalophora, Bl.
divided into the orders Pulmobranchiata, Chismobranchiata,
Monopleurobranchiata, in the first section; and Aporobranchiata,
Polybranchiata, Cyclobranchiata, Inferobranchiata, and
Nucleobranchiata, in the second.
MONOMYARIA. Lam. ([Greek: Monos], _monos_, single; [Greek: muon],
_myon_, muscle.) The second order of Conchifera, consisting of those
bivalve shells which have but _one_ principal muscular impression in
each valve. The Monomyaria are thus divided: First section, containing
the families Tridacnacea, Mytilacea, Malleacea; second section,
containing the families Pectinides, Ostracea; third section, containing
the families Rudistes, Brachiopoda.
MONOPLEUROBRANCHIATA. Bl. The second order of the first section of
Paracephalophora Monoica. Bl. The animals are described as having the
lungs branched, situated at the right side of the body and covered more
or less completely by the operculiform mantle, in which there is
sometimes enveloped either a flat or a more or less involute shell,
with a large entire aperture. They have either rudimentary or auricular
tentacula, or none. This order, which includes mollusca with haliotoid
or patelliform shells, is divided into the following families: _Fam._
Subaplysiacea; 2. Aplysiacea; 3. Patelloidea; 4. Acera.
MONOPTYGMA. Lea. A genus of small shells resembling Tornatella, but
having a strong, oblique fold in the centre of the columellar lip. M.
Elegans, fig. 344.
MONOTHALAMIA. ([Greek: Monos], _monos_, single; [Greek: thalamos],
_thalamos_, chamber.) The second division of Cephalopoda, Lam.
containing only one genus, namely Argonauta.
MONOTHYRA. A term used by Aristotle to designate spiral univalves.
MONOTIGMA. Gray. A genus founded on the species represented fig. 371.
It is a turrited shell, but we are unacquainted with the characters of
the genus.
MORIO. Montf. CASSIDARIA, Auct. C. Echinophora, fig. 407.
MOTHER OF PEARL. This beautiful substance, which is so much resorted to
for ornamental purposes, constitutes the thickened coating of the
internal surface of the shell named by scientific collectors,
Meleagrina Margaritifera, commonly called the Pearl Oyster, a young
specimen of which is figured (164) in our plates. The reason why this
substance is called mother-of-pearl is that the true pearls are
produced from its surface. They arise principally from accident or
disease, and are sometimes artificially produced by pricking through
the outside of the shell while the animal is living. The animal is
allowed to live until it has formed a pearl over the wounded part.
MOULINSIA. Grateloup. PUPINA, Vignard. A
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