A Conchological Manual by George Brettingham Sowerby (early reader books .txt) 📖
- Author: George Brettingham Sowerby
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species of Nautilus as have been compressed, so as to assume an oval
instead of a round form. The genus Ellipsolites of De Montfort consists
of species of Ammonites similarly deformed.
NAUTILACEA. Bl. The fifth family of Polythalamacea, Bl. the shells of
which are described as more or less discoidal, compressed,
symmetrically convolute; the last whorl much longer than the others;
which are entirely hidden beneath it and advancing beyond the last but
one, so as constantly to form a large oval aperture, which is always,
however, modified by the last whorl. The septa are united in the
greater number of instances and pierced by one or more (?) siphons.
This family contains the genera Orbulites, Nautilus, Polystomella and
Lenticulina.
NAUTILACEA. Lam. The sixth family of Polythalamous Cephalopoda, Lam.
containing the genera Discorbites, Siderolites, Polystomella,
Vorticialis, Nummulites, Nautilus. To these may be added Simplegas and
Endosiphonites. Fig. 472 to 476.
NAUTILUS. Auct. (_A little boat._) _Fam._ Nautilacea, Lam. and
Bl.--_Descr._ Convolute, discoid, chambered, symmetrical; spire partly
or entirely concealed by the last whorl; aperture modified by the last
whorl, wide, sinuated on the dorsal margin; interior surface pearly;
septa dividing the chambers simple; siphon discontinuous.--_Obs._ The
shell named Nautilus by Pliny is the Argonauta of modern authors, a
thin shell, not chambered. The Nautili are known from the Ammonites by
the septa being simple, not sinuated as in the latter genus, and in
general the volutions of the spire are not visible. Three or four
species are known inhabitants of the Pacific Ocean and Australian
Ocean. The fossil species are found in the tertiary, and also in the
secondary strata, as low down as the Mountain limestone. N. pompilius,
Frontispiece.
NAYADES. Lam. A family of the order Conchifera Dimyaria, Lam. described
as containing fresh-water bivalve shells, with or without teeth on the
hinge. They are all pearly within, and have a thick, rather smooth
epidermis without. This family contains a great variety of shells,
which have been separated into an immense number of genera, but which
B. Sowerby, sen. gives very good reasons for uniting under onegeneric name. The most generally received distinctions are as follows:
CASTALIA. Two cardinal, one lateral, ribbed teeth. This genus is
removed from the family of Trigonacea. Fig. 140.
UNIO. Teeth various. Fig. 142, 145, 149, 148, 147, 151, 141.
HYRIA. Trigonal, alated. Fig. 143, 150.
ANODON. No teeth. Fig. 152.
IRIDINA. Hinge crenated. Fig. 150.
NECTOPODA. Bl. The first family Nucleobranchiata, Bl. containing the
genera Carinaria and Firola; the latter is not a shell.
NEMATOPODA. Bl. The first class of the sub-type Malentozoa, Bl.
containing all the mollusca with multivalve shells, except Chiton, and
divided into the families Lepadicea and Balanidea, corresponding with
Lamarck's sessile and pedunculated Cirripedes, and with the Linnæan
genus Lepas.
NEMATURA. Benson. _Fam._ Turbinacea, Lam.--_Descr._ Thin, nearly oval,
somewhat compressed from back to front; spire acute, consisting of few
rounded whorls; last whorl large, but contracted near the aperture;
aperture small, oblique, rounded anteriorly; peritreme continuous,
thin; operculum spiral, horny, with few volutions.--_Obs._ The
distinguishing character of this genus is the contraction of the last
whorl near the aperture, in which respect it is nearly resembled by the
shell called Cyclostoma lucidum. Two recent and one fossil species, all
very minute, are described by Sowerby in Loudon's Magazine of Natural
History, New Series. Fig. 305.
NERINEA. Defr. _Fam._ Canalifera, Lam.--_Descr._ Turrited, oblong,
sub-canaliculated, consisting of numerous whorls; aperture with a
strong fold on the columella, one on the outer lip, and one on the
inner lip at the edge of the body whorl.--_Obs._ This genus is only
found in a fossil state usually in the Oolitic beds, it is not
resembled by any other; the strong, prominent folds on the three upper
angles of the subquadrate aperture present a singular appearance in a
section. One species has been named N. Hieroglyphus. We give N.
Goodhallii, fig. 374.
NERITA. Auct. _Fam._ Neritacea, Lam. Hemicyclostomata, Bl.--_Descr._
Smooth or ribbed, semiglobose; spire short, sometimes flat, consisting
of few volutions; aperture large, semilunar; outer lip thick, entire;
inner lip thickened, dentated at the edge, spread over the body whorl,
forming a flattened disc; operculum shelly, spiral, with an appendage
by which it is locked under the sharp edge of the columella.--_Obs._
These marine shells are known from Neritina by the thickness of the
shell and the want of the thick, horny, dark coloured epidermis; from
Natica by the flat area produced by the spreading of the thickened
columellar lip. N. Peloronta, fig. 330. N. polita, fig. 329.
NERITACEA. Lam. A family of the first order of Trachelipoda, Lam.
containing the following genera:
NAVICELLA. Apex terminal, not spiral; inner lip septiform. Fig.
323.
NERITA. Columellar lip septiform, edge with distinct teeth;
shell thick. Fig. 330.
NERITINA. Shell thin; columellar lip septiform, edge
denticulated; generally a thick, dark coloured epidermis. Fig. 324
to 326.
NATICA. Having an umbilicus behind the columellar lip, with a
spiral callosity. Fig. 327, 328.
NERITOPSIS. Edge of the columellar lip with a deep notch. Fig.
331.
PILEOLUS. Patelliform; apex central; columellar lip septiform,
leaving the aperture small. Fig. 332.
JANTHINA. Columellar lip linear; aperture angulated. Fig. 333.
NERITINA. Lam. _Fam._ Neritacea, Lam.--_Descr._ Thin, semiglobose,
obliquely oval, smooth, flattish in front; spire short, sometimes
depressed, consisting of few rapidly increasing whorls; aperture
semicircular; outer lip thin, sharp; columellar lip broad, flat, its
inner edge straight, denticulated; operculum testaceous, semicircular,
sub-spiral, with an articulating process on the inner edge.--_Obs._
This genus of fresh-water shells differs from Nerita in the minuteness
of the denticulation of the columella, as well as in the characters
mentioned in our observations upon the latter genus. N. spinosa,
(Clithon, Montf.) fig. 325. N. virginea, fig. 324. N. perversa, Lam.
(Velates, Montf.) fig. 326. All the species known up to the present
time, with the exception of three, are represented in the author's
Conchological Illustrations, parts 86, 87, 90, 91, 94 to 100. The
catalogue accompanying these representations enumerates 59 species.
NERITOPSIS. Gray. _Fam._ Neritacea, Lam.--_Descr._ Sub-globose, thick,
cancellated; spire short, composed of few rapidly increasing whorls;
aperture transverse, sub-orbicular; outer lip thickened within;
columellar lip thick, rather flat, with a large rounded notch in the
centre of its inner edge.--_Obs._ This genus most nearly resembles
Nerita, from which it differs in the peculiar notch of the columella.
granosa, fig. 331.
NICANIA. Leach. ASTARTE, Sowerby. The same as CRASSINA of Lamarck.
NITIDELLA. Sw. A genus of "Columbellinæ," Sw. thus described:
"Bucciniform, small, ovate, smooth, glassy; aperture effuse; outer lip
slightly thickened, faintly inflexed, and generally striated
internally; inner lip somewhat flattened above; base of the pillar with
one or two slight internal folds, or a single angular projection.
Columbella nitida, _Lam._ (fig. 17, _c._ p. 151.)" Sw. p. 313.
NOBIA. Leach. _Order_, Sessile Cirripedes, Lam. This genus resembles
Pyrgoma, Auct. consisting of a conical paries, supported upon a
funnel-shaped cavity in the madrepore, but differs in its operculum,
which consists of two valves, whereas that of Pyrgoma has four. N.
grandis, fig. 29.
NODOSARIA. Lam. and ORTHOCERA have been united by Sowerby under the
name of the first. _Fam._ Orthocerata, Lam. and Bl.--_Descr._ Straight,
chambered, elongated; chambers more or less ventricose; septa
perforated by a central siphon.--_Obs._ This genus consists only of
fossils found in sub-appenine tertiary beds. It is placed by De
Blainville in one of his divisions of the genus Orthoceras, which is
characterized as "species not striated, and with chambers very much
inflated." N. æqualis, fig. 465.
NODOSE. Having tubercles or knobs.
NOGROBS. Montf. A fossil appearing from the figure and description to
resemble Belemnites.
NONION. Montf. A genus of microscopic Foraminifera.
NONIONINA. D'Orb. A genus of microscopic Foraminifera.
NOTREMA. Rafinesque. A shell described as composed of three integral
valves, concerning which De Blainville puts the query, "ne seroit-ce
pas plutôt une Balanide mal observée?"
NOVACULINA. Benson. (_Novacula_, a razor.) _Fam._ Solenacea,
Lam.--_Descr._ Equivalve, inequilateral, transversely elongated;
external ligament communicating with the interior of the shell by an
oblique channel; beaks prominent; hinge line nearly straight, with one
narrow curved cardinal tooth in one valve, entering between two similar
teeth in the other; siphonal scar long; extremities of the shell
gaping; epidermis thin, light brown, folding over the edges and
connecting the dorsal margins. _Hab._ Jumna, Gooti, and Ganges. Fig.
63.
NUCLEOBRANCHIATA. Bl. The fifth order of the second section of
Paracephalophora Monoica, Bl. the shells of which are described as
symmetrical, more or less curved, or longitudinally rolled up and very
thin. This order contains, _Fam._ 1. Nectopoda, containing Carinaria;
_Fam._ 2. Pteropoda, containing Atlanta, Spiratella and Argonauta.
NUCLEUS. (_A kernel._) Anything forming a centre around which matter is
gathered. The nucleus of shells is the first formed part; the first
deposit of shelly matter to which the successive layers are added; the
apex of the spiral cone, of which most shells are composed. (See CONE.)
The nucleus is formed within the egg in oviparous, and within the old
shell in viviparous mollusca. It is frequently more transparent and
light than the remainder of the shell, and sometimes falls off; when
this occurs the shell is said to be decollated.
NUCULA. Lam. (_A small nut._) _Fam._ Arcacea, Bl. and Lam.--_Descr._
Equivalve, inequilateral, transverse, covered with an epidermis; hinge
linear, with a series of sharp, angulated teeth, arranged in a line on
each side of the umbones, and a central ligamentary pit; muscular
impressions two, simple; palleal impressions not sinuated.--_Obs._ The
row of teeth on each side of the umbones, and the ligamentary pit in
the centre of the hinge prevent the pretty little shells of this genus
from being confounded with any other. Thirty-four figures are
enumerated in the catalogue by Sowerby, sen. which accompanies the
Conchological Illustrations of the author. The new species, to the
amount of 24, have been figured in parts 14 to 16, of the above
mentioned work. Recent Nuculæ are found from the frozen to the torrid
zones, and the fossil species occur in nearly all the beds from the
Pliocene to the Carboniferous system.
NUMMULACEA. Bl. The third family of Cellulacea, Bl. described as
containing shells or calcareous bodies, which are characterized as
discoidal, lenticular; without the slightest traces of whorls to be
seen externally. The whorls are numerous, internal, and divided into a
great number of cells, which are separated from each other by
imperforate septa. This family contains the genera Nummulites,
Siderolites, Vorticialis, Helicites, Orbiculina, Placentula.
NUMMULTTES. Lam. (_Nummus_, money.) _Fam._ Nautilacea, Lam.--_Descr._
Orbicular, convolute, shewing no trace of spire externally; interior
divided into cells spirally arranged.--_Obs._ The singular fossils
composing this genus receive their name from their external resemblance
to a battered coin. Fig. 472. N. lenticulina.
NUX. Humph. CYCLAS, Lam.
NYMPHACEA. Lam. A family belonging to the order Conchifera Dimyaria,
Lam. Ligament external, placed on a prominent fulcrum. This family
contains the following genera:
SANGUINOLARIA. Rostrated, gaping; two cardinal teeth in each
valve, including _Soletellina_ and _Lobaria_. Fig. 98, 99.
PSAMMOBIA. Quadrate; valves closed, including Psammotæa. Fig.
100.
CORBIS. Thick, fimbriated; a cardinal tooth in the centre of a
pit. Fig. 101.
GRATELOUPIA. A series of small teeth filling a triangular area.
Fig. 102.
EGERIA. One single and one double cardinal tooth. Fig. 103.
LUCINA. Rounded; anterior muscular impression tongue-shaped.
Fig. 104.
TELLINA. An anterior fold in the ventral margin; lateral teeth.
Fig. 105, 106.
TELLINIDES. No anterior fold; no lateral teeth. Fig. 107.
DONAX. Margin denticulated; shell wedge-shaped. Fig. 108.
CAPSA. Margin not denticulated, no lateral teeth. Fig. 109.
OBELISCUS. Humph. TROCHUS, Lam.
OBLIQUE. (_obliquus._ lat.) In a slanting direction. The whorls of
spiral univalves generally take an oblique direction in reference to
the imaginary axis of the shell. A bivalve is said to be oblique when
it slants off from the umbones. An example of this is seen in Avicula,
fig. 163.
OBSOLETE. (_obsoletus_, lat.) Worn out, out of use. This term is used
to express an indistinctness of character, which sometimes results from
the action of sea-water upon unprotected parts of the shell, and
sometimes from the deposits of enamel formed in age, and covering the
early striæ, ribs, teeth, &c. thereby rendering them less acute.
OBTUSE. (_obtusus_, blunt.) The application of this term is
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