A Conchological Manual by George Brettingham Sowerby (early reader books .txt) 📖
- Author: George Brettingham Sowerby
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peculiar to conchology. It is most frequently used to express the
character of the spire. _Ex_. The apex of Megaspira, fig. 294.
OCEANUS. Montf. ("Corne d'ammon vivant," Fr.) NAUTILUS umbilicatus,
Auct.
OCTHOSIA. Ranz. CLITIA, Leach.
OCTOCERA. Bl. The first family of the order Cryptodibranchiata, Bl.
containing the genus Octopus. A species of which being found in the
Argonauta, or Paper Sailor, has given rise to the long continued
controversy as to whether it is really the constructor of the shell, or
whether it is a mere pirate, and having destroyed the true animal of
the Argonaut, has possessed itself of the habitation. This question is
now set at rest. See ARGONAUTA.
OCTOGONAL. (_octogonum._) Having eight angles. For an example, see
Dentalium, fig. 2.
OCTOMERIS. Sow. ([Greek: oktô], _octo_, eight; [Greek: meros], _meros_,
part.) _Fam._ Balanidea, Bl. _Order_, Sessile Cirripedes,
Lam.--_Descr._ Eight principal valves circularly arranged, forming a
compressed cone, attached by a jagged base; aperture enclosed by an
operculum, consisting of four valves in pairs.--_Obs._ The only genus
of Sessile Cirripedes agreeing with this in the number of principal
valves is Catophragmus, Sow. which is, however, sufficiently
distinguished by the several rows of smaller valves by which the
principals are surrounded at the base. O. angulosus, fig. 24.
ODONTIS. Sow. MONODONTA, Lam.
ODOSTOMIA. Flem. _Descr._ "Shell conical; aperture ovate; peristome
incomplete, retrally, and furnished with a tooth on the pillar." A
genus composed of several small species of land shells. Turbo plicatus,
Spiralis, Unidentatus, &c. Mont.
OLIVA. Auct. (_An olive._) _Fam._ Convoluta, Lam. Angyostomata.
Bl.--_Descr._ Oblong, cylindrical, thick, smooth, shining; spire very
short, with sutures distinct, aperture elongated, notched at both
extremities; outer lip generally thick; columella thick, obliquely
striated, terminated by a tumid, oblique, striated varix; a raised band
passing round the lower part of the body whorl.--_Obs._ The shells
composing this well known genus present a great variety of rich
markings and brilliant colours. They are marine and tropical. Fossil
species are found sparingly in the London Clay and Calcaire-grossièr.
The Ancillariæ are distinguished from this genus by the sutures of the
whorls being covered by enamel. O. maura, fig. 457.
OLIVELLA. Sw. A genus of "Olivinæ," Sw. thus described: "Oliviform;
spire (typically) rather produced; the tip acute; inner lip not
thickened; outer lip straight; base of the pillar curved inwards, and
marked by two strong plaits; upper plaits obsolete or wanting; aperture
effused at the base only; biplicata, Tank. Cat. 2332. purpurata. Zool.
Ill. ii. 58. f. 1. mutabilis. _Say._ eburnea. Zool. Ill. ii. 58, f. 2.
conoidalis. _Lam._ No. 57. oryza. _Lam._ No. 62."
OLYGYRA. Say. Mentioned by Ranz as properly belonging to Helicina. H.
neritella, Auct.
OMALAXIS. Desh. Subsequently BIFRONTIA. Desh. Fig. 354.
ONISCIA. Sow. (G. B.) _Fam._ Purpurifera, Lam. Entomostomata,
Bl.--_Descr._ Oblong, sub-ovate, slightly turbinated, cancellated;
spire short; aperture elongated; terminating anteriorly in a very
short, recurved canal; outer lip thickened, denticulated within; inner
lip spread over a portion of the body whorl, granulated.--_Obs._ The
granulated inner lip is the principal character by which this genus is
distinguished from Cassidaria. In Oniscia the canal is not so produced.
oniscus, fig. 409.
ONUSTUS. Humph. A genus proposed by Humphrey and adopted by Swainson
who describes it thus: "Shell trochiform; the surface irregular, and
often covered with extraneous bodies, cemented and incorporated with
the calcareous substance of the shell; the under part of the body whorl
flattened or concave, umbilicate. O. Solaris. Mart. 173. f. 1700, 1701.
Indicus. Ib. 172. f. 1697. 1698." It is probable, from the above
description, that Mr. Swainson intended to include Trochus agglutinans
of authors. (Genus Phorus, Montf.) Fig. 360.
OPERCULAR. Of, or belonging to, the operculum. A term applied to the
valves which compose the operculum of multivalve shells, as
distinguished from the parietal valves, or those which are arranged
circularly and form the body of the shell.
OPERCULINA. D'Orb. A genus of microscopic Foraminifera.
OPERCULUM. (_A cover or lid._) The plate or plates with which many
molluscous animals enclose the aperture of their shells, when retired
within them. The operculum is sometimes horny, as in Trochus;
testaceous or shelly, as in Turbo. It is spiral when from a central or
sub-central nucleus, the successive layers take a revolving direction,
as in Trochus. It is concentric or annular when the outside edge of
each layer entirely surrounds the preceding one. It is unguiculated,
when the laminæ are placed side by side, as in Purpura. The opercula of
multivalve shells are composed of two or four pieces, which are called
the opercular valves. 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. It is called the epiphragm, and may easily be
distinguished from the true operculum by the texture, and by the
circumstance of their being soldered to the edge of the aperture. The
operculum, on the contrary, is moveable, and is always composed of a
series of successive layers, corresponding with the growth of the
shell.
OPIS. Defr. A genus described by De Blainville as consisting of species
of Trigonia which have the umbones sub-spiral, with a large, striated
tooth on the hinge. Opis cardissoides, Trigonia, Lam. Opis similis,
Sow. Min. Con. pl. 232. f. 2.
ORAL. (_Os_, _oris_, mouth.) Applied to that part of a shell which
corresponds with the mouth of the animal, but very seldom used in this
sense.
ORBICULA. Lam. (_Orbis_, an orb.) _Fam._ Brachiopoda, Lam.
Palliobranchiata, Bl.--_Descr._ Inequivalve, irregular, sub-orbicular,
compressed, attached by a fibrous substance passing through a fissure
near the centre of the lower valve; upper valve patelliform, with the
umbo central; muscular impressions four in each valve, semilunar. South
America and West Indies.--_Obs._ Discina, Lam. is an Orbicula. Crania
is known from this genus by having no fissure in the lower valve, but
being attached by its substance. Hipponyx has only two muscular
impressions in each valve. O. lævis, fig. 201.
ORBICULAR. (_Orbiculus_, a little orb.) Of a round or circular form.
ORBICULINA. Lam. A genus of microscopic Foraminifera.
ORBIS. Lea. A minute fossil, described as "orbicular, with flat
quadrate whorls and aperture square," in other respects resembling
Solarium. O. Rotella, fig. 355, 356.
ORBITINA. Risso. A genus said to be established upon the nuclei of two
land shells.
ORBULITES. Lam. A genus separated from Ammonites on account of the last
volution covering the spire. This is generally considered as
characterizing the Nautili, and distinguishing them from the Ammonites;
but there are so many gradations that it seems impossible to maintain
the distinction in this respect. Fig. 479, O. crassus, fig. 480, O.
discus.
OREAS. Montf. Part of CRISTELLARIA, Lam. A genus of microscopic
Foraminifera.
ORTHIS. Dalman. ([Greek: orthos], _orthos_, straight.) _Fam._
Brachiopoda, Lam. One of the generic divisions of Brachiopoda by
Dalman, thus described: "Hinge rectilinear, with umbones distant; the
larger valve with a transverse, basal, smooth area, with a triangular
pit." O. basalis, fig. 207.
ORTHOCERA. Lam. See NODOSARIA.
ORTHOCERATA. Lam. A family of Polythalamous Cephalopoda, Lam.
containing the following genera:--
CONULARIA. Conical, externally striated; no siphon. Fig. 469.
AMPLEXUS. Cylindrical; margins of the septa reflected. Fig. 463.
ORTHOCERATITES. Straight, gradually conical; septa simple;
siphon central. Fig. 464.
NODOSARIA. Divided externally into lobes. Fig. 465.
BELEMNITES. Straight, conical; septa simple; siphon lateral;
apex solid; internal cast, or nucleus, pyramidal, separable. Fig.
466 to 468.
CONILITES. Like Belemnites, but external shell thin at the apex.
Fig. 470.
ORTHOCERATA. Bl. The first family of Polythalamacea, Bl. containing the
genera Belemnites, Conularia, Conilites, Orthoceras and Baculites. De
Blainville remarks that the genera included in this family are all
fossils, and known very imperfectly, in consequence of the greater part
of the specimens being only casts.
ORTHOCERATITES. Auct. _Fam._ Orthocerata, Lam. and Bl.--_Descr._
Straight, conical, divided into numerous chambers by simple septa
perforated by a central siphon. O. annulata, fig. 464.
OSTEODESMA. Desh. PERIPLOMA, Schum.
OSTRACEA. (_Ostracées_, Lam.) A family belonging to the second section
of the order Conchifera Monomyaria, the shells of which are described
as irregular, foliaceous, sometimes papyraceous, with the ligament
wholly or partly interior. The principal difference between the
Ostracea and the Pectinides consists in the absence of the auricles and
the foliated structure of the shells, for, although the Spondylus has
ex-foliations or spines upon the external surface, the shell itself is
compact and firm. This family contains the genera Gryphæa, Ostrea,
Vulsella, Placuna, Anomia, which may be thus distinguished:--
PEDUM. Flat, turned up at the sides, an hiatus for the passage
of a byssus. A triangular disc on the hinge. Fig. 179.
OSTREA. Foliaceous, irregular, hinge on a small triangular disc.
Including Dendostrea, Ostræa, Exogyra, Gryphæa. Fig. 180 to 183.
PLACUNA. Two diverging ribs near the umbones. Fig. 184.
PLACUNANOMIA. The same, but attached by fibres passing through a
hole in one valve. Fig. 189 to 191.
ANOMIA. No costæ, attached by a bony substance passing through a
hole in one valve. Fig. 186 to 188.
VULSELLA. Tongue-shaped, a ligamentary pit on the hinge. Fig.
185.
MULLERIA. Doubtful. Fig. 192.
OSTRACEA. Bl. The first family of the order Lamellibranchiata, Bl.
containing the genera Anomia, Placuna, Harpax, Ostrea (including
Dendostrea, Sw.) Gryphæa. To these may be added Placunanomia, Brod. and
Mulleria.
OSTREA. Auct. ([Greek: ostreon], _ostreon_, a bone.) _Fam._ Ostracea,
Lam. and Bl.--_Descr._ Irregular, inequivalve, generally inequilateral,
foliaceous, attached by part of the lower valve; hinge sometimes
slightly crenated; destitute of teeth; with the ligament spread upon
the lower part of a central, triangular area, which is divided into
three parts; upper valve much flatter than the lower; muscular
impressions one in each valve, large, sub-central, sub-orbicular, with
one very minute.--_Obs._ The Linnæan Genus Ostrea includes the Pectens
and many other genera so different from each other that, without any
desire to increase the number of genera, it was found necessary by
subsequent authors to separate them. The common Oyster is the type of
this genus as at present constituted, and is well known to be abundant
in various parts of the world. Those which depart furthest from this
type are the Gryphæa, Lam. with a prominent, incurved umbo in the lower
valve. The Dendostrea, Sw. with margins characterized by strongly
angulated folds, throws out arms from the lower valve, by which they
are attached to stems of sea-weed, &c. Fig. 180, O. edulis. Fig. 181,
folium. (Dendostrea, Sw.) Fig. 182, Gryphæa incurva. Fig. 183,Exogyra conica.
OTIDES. Bl. The first order of Scutibranchiata, Bl. containing the
genera Haliotis and Ancylus.
OTION. Leach. ([Greek: ôtion], a little ear.) _Order._ Pedunculated
Cirripedes, Lam.--_Descr._ Body sub-quadrate, supported on a fleshy
pedicle with a gaping aperture and two posterior auricular tubes;
valves five, separate, two semilunar, placed at the sides of the
aperture, two terminal, very small, one dorsal, minute.--_Obs._ Otion
differs from Cineras in having two cylindrical posterior tubes, and in
the extreme minuteness of three out of five of the valves. Found on
spars floating in the sea, &c. O. Cuvierii, (Lepas aurita, Linn.) Fig.
43, O. Cuvieri.
OTIS. Humph. AURICULA, Lam.
OVATE. (_Ovatus._) Egg-shaped or oval.
OVEOLITHES. Montf. A microscopic shell resembling Bulla.
OVIPAROUS MOLLUSCA. Those which produce their young in eggs. Used in
distinction from the VIVIPAROUS MOLLUSCA, whose young are perfectly
formed before they leave the body of the parent.
OUTER LIP. See LABRUM.
OVULUM. Brug. (_Ovum_, an egg, dim.) _Fam._ Convoluta, Lam.
Angyostomata, Bl.--_Descr._ Ovate or fusiform, smooth, convolute, spire
covered; aperture narrow, with a canal at each extremity; outer lip
crenulated, inflected; inner lip smooth, callous towards the spiral
extremity; dorsal area wide, sometimes indistinctly marked.--_Obs._ The
Ovula were placed by Linnæus in his genus Bulla, from which they are
very remote. They differ from Cypræa in having the inner lip
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