A Conchological Manual by George Brettingham Sowerby (early reader books .txt) 📖
- Author: George Brettingham Sowerby
Book online «A Conchological Manual by George Brettingham Sowerby (early reader books .txt) 📖». Author George Brettingham Sowerby
outer lip reflected, denticulated on the inner edge. Suture of the
whorls covered with enamel.--_Obs._ This genus of shells resembles
Marginella in form, but has no folds on the columella. Having a scar or
groove down the back it may be considered intermediate between
Marginella and Cypræa. Fig. 454, E. Maugeriæ. In the Author's
Conchological Illustrations, seven species are enumerated and figured.
ERUCA. Sw. A subgenus of Clausilia. Sw. Malac. p. 334.
ERVILIA. Turt. A genus described as "oval, equivalve, equilateral,
closed. Hinge with a single erect tooth closing between two small
diverging ones in the opposite valve: lateral teeth none. Ligament
internal. E. nitens. Turt. Mya. nitens, Auct."
ERYCINA. Lam. _Fam._ Mactracea, Lam. Conchacea, Bl.--_Descr._ Ovate or
triangular, transverse, equivalve, inequilateral, smooth; hinge with a
ligamentary pit, two diverging cardinal and two lateral teeth in each
valve; muscular impressions two in each valve; palleal impressions
sinuated. East and West Indies and Mediterranean.--_Obs._ This genus is
distinguished from _Mactra_ and _Lutraria_ by the cardinal teeth being
placed one on each side of the ligamentiferous pit; whereas in the last
named genera they are both placed on the anterior side. Fig. 86, E.
Plebeja.
ERYTHRÆA. The ancient name for CYPRÆA.
ESCUTCHEON. The impression on the posterior dorsal margin of some
bivalve shells. That on the anterior margin is named the lunule. The
escutcheon is pointed out by the letter _e_ in some of the figures of
Cythereæ. Fig. 117, _a. b. c._
ETHERIA. Lam. (_Æther_, air.) Fam. Chamacea, Lam. and Bl.--_Descr._
Irregular, inequivalve, inequilateral, foliaceous, pearly within,
covered by an olive green epidermis without; hinge callous, undulated,
destitute of teeth; ligament partly external, partly internal, passing
through the hinge on a somewhat raised, callous area in the lower
valve. Muscular impressions elongated, two in each valve, united by a
slender palleal impression. Rivers of Africa.--_Obs._ The irregular,
unequal air-bubbles of the inner surface, whence this genus derives its
name, are very brilliant in some species, and atone, in some measure,
for the rugged ugliness of the exterior. In its irregular form,
foliated structure, and toothless hinge, it resembles OSTREA, from
which it differs in having two muscular impressions. Fig. 155, E.
semilunata.
EULIMA. Risso. _Fam._ Scalariens, Lam.--_Descr._ Elongated, smooth,
pyramidal; spire long, composed of numerous whorls; apex acute,
slightly tortuous; aperture oval, rounded anteriorly, acute at the
posterior union with the body whorl; outer lip slightly thickened;
columella smooth. Fig. 347, E. labiosa, fig. 348, E. splendidula. A
complete illustrated monograph of this genus of pretty shining little
shells, consisting of 15 known species, is given in parts 52 and 53 of
the Conchological Illustrations by the author.
EUOMPHALUS. Sow. _Fam._ Scalariens, Lam.--_Descr._ Orbicular,
planorbular spire, with three or four volutions, imbricated above;
smooth below; aperture of a round polygonal form; umbilicus large,
penetrating to the apex of the shell.--_Obs._ This genus of fossils
very nearly resembles Delphinula. The main difference appears to be
that the whorls do not increase so rapidly in size in the former as in
the latter. Fossil, in the Carboniferous Limestone. Fig. 350.
EXOGYRA. Sow. A genus of fossil bivalves, resembling Chama in shape and
Ostræa in structure, having but one muscular impression in each valve.
Fig. 183.
EXSERTED. Standing out, protruding.
EXTERNAL. An external shell is one which contains the animal, and is
not covered by the mantle.
FASCIATED. (_fascia_, a band.) Banded or striped. Ex. Carocolla
marginata, fig. 277.
FASCICULATED. (from fasciculum.) A little bunch of hairs or bristles
against each end of each valve, characterizes some species of the genus
Chiton, which are termed fasciculated species.
FASCIOLARIA. Lam. _Fam._ Canalifera, Lam. Siphonostomata, Bl.--_Descr._
Elongated, fusiform, ventricose; spire conical, consisting of few
rounded or angulated whorls; aperture wide, terminating in a long
straight open canal: columella lip with several oblique folds, the
lower of which is larger than the rest; operculum horny,
pyriform.--_Obs._ This genus is known from Fusus by the folds on the
columella; from Turbinella, by their obliquity and the last being
larger than the rest. Fig. 386, F. Trapezium. East and West Indies and
Australia.
FAUNUS. Montf. MELANOPSIS, Auct.
FERRUGINEOUS. Of an iron rust colour.
FERUSSINA. Grateloup. STROPHOSTOMA, Deshayes.
FIBROUS. A shell is said to be of a fibrous structure when a fracture
would present a series of perpendicular fibres, as Pinna.
FICULA. Sw. A generic group of shells, consisting of those species of
PYRULA, Auct. which have the true pear-shaped character. Fig. 390, P.
Ficus. Sowerby confines the name Pyrula to these species.
FIMBRIA. Megerle. CORBIS, Lam.
FIMBRIATED. Fringed; as Murex fimbriatus, a delicate white species,
with broad fringed varices.
FISSURE. (_Fissura_, a slit.) A slit or cut, a narrow perforation, as
in Emarginula and Fissurella.
FISSURELLA. Brug. (_Fissura_, a fissure.) _Fam._ Calyptracia, Lam.
Branchifera, Bl.--_Descr._ Patelliform, oval or oblong, radiated; apex
anterior, perforated.--_Obs._ The Fissurellæ are known from Patellæ by
the perforation in the apex. Fig. 245. The catalogue published by the
author in the Conchological Illustrations, enumerates 68 species.
FISTULANA. Lam. (_Fistula_, a pipe.) _Fam._ Tubicolæ, Lam. Adesmacea,
Bl.--_Descr._ A transversely elongated, equivalve, inequilateral
bivalve, enclosed by a septum within the widest, closed extremity of a
straight calcareous tube. Fistulana is known from Gastrochæna by the
straightness of the tubes, and the oblong state of the valves. Fig. 54,
Fistulana Clava.
FLEXUOUS. Having windings or bendings. _Ex._ The Tellinæ are known by
the twist or flexuosity in the posterior ventral margin of the shell.
FLORILLUS. Montf. A genus of microscopic Foraminifera.
FLUVIATILE. (Fluviatilis.) Belonging to a river or running stream.
_Ex._ Limnæa fluviatilis.
FLUVIATILE CONCHACEA. See CONCHACEA.
FOLIATED, or FOLIACEOUS. (From _folium_, a leaf.) When the edges of the
successive layers of which a shell is composed are not compacted but
placed apart from each other, projecting like tiles, the shell is said
to be of a foliated structure. The common Oyster, fig. 180, presents a
familiar example.
FORAMINIFERA. D'Orb. (_Foramen_, a hole or pit.) An order established
for minute many chambered internal shells, which have no open chamber
beyond the last partition. Lamarck, D'Orbigny, and other writers have
placed them among the Cephalopoda in their systems, but Du Jardin, on
comparing the fossils with some recent species of the same class,
arrived at the conclusion, now generally adopted, that they constitute
a distinct class, much lower in degree of organization than even the
Radiata. Not recognizing these microscopic bodies as shells, properly
so called, but considering them sufficiently numerous and interesting
to form a distinct branch of study, I do not think it desirable to
describe the genera, or to present any arrangement of them in this
work.
FORNICATED. Arched or vaulted, as the exfoliations on the costæ of
Tridacna Elongata, fig. 157.
FOSSIL SHELL. A shell is considered to be in a fossil state when, the
soft parts having ceased to exist, it is deprived of all its animal
juices, has lost all, or nearly all its natural colour, and is thus
changed in its chemical composition, when little or nothing is left but
a mere bone, which is embedded in a sedimentary deposit. In this state,
it is fragile, prehensile to the tongue, and either destitute of colour
or tinged with the diluted mineral matters which pervade the stratum in
which it lies. In some cases, the mineral composition of the shell is
so completely changed as no longer to present its proper structure,
consisting of successive oblique layers of shelly matter; but is
altered into a fibrous structure, composed of rhomboidal particles. An
example of this will be found in the Belemnites, which if broken, shew
the perpendicular fibres. In other cases, the matter which has entered
and filled up the cavities of the shell has become silicified, or
changed into flint, and the shell itself has been decomposed and fallen
off, so as to leave nothing but an external or internal cast of its
form, in flint. This is called a Conchyliomorphite by continental
writers. Some of the most important of Geological data are obtained by
a minute comparison of fossil shells, found in various beds, with
recent ones presenting the nearest resemblance to them. Some species of
fossil shells are considered as identical with recent species. And many
Geologists seek to fix the chronology of the different strata by the
number of species which they inclose bearing a resemblance to the
recent species. Indeed, all who would study Geology with success, will
find it indispensably necessary to obtain a thorough knowledge of
Conchology.
FRAGELLA. Sw. A sub-genus of Monodonta, corresponding with the genus
Clanculus, Montf. consisting of M. Pharaonis (fig. 361), and similar
species. Sw. p. 352.
FRAGILE. (_Fragilis._) Tender, easily broken.
FREE SHELL. One that is not attached.
FREE VALVE. In attached bivalve shells, one only is fixed; the other is
then _free_, as far as to the action of opening and shutting.
FRESH-WATER SHELLS, (sometimes described as aquatic) are those which
either inhabit rivers, running pools and ditches, in which case they
are _fluviatile_; or wells and ponds of standing water, &c. Fresh-water
shells are either thin and horny in their texture, as the Limneana of
Lamarck; or are covered with a compact, smooth, horny epidermis. They
are generally simple in form, subject to corrosion where the epidermis
is wounded or broken, and are circumscribed with regard to the classes
and genera to which they belong. The family of Nayades includes nearly
all the fresh-water bivalves; and the Melaniana and Limneana are the
principal among univalves.
FRONDICULARIA. Defr. A genus of microscopic Foraminifera.
FRONT. The surface of a shell on which the aperture appears.
FULCRUM. That part of a shell on which any other part rests or turns.
The term is applied more particularly to the tumid part in the hinge of
bivalve shells on which the ligament is fixed.
FULGUR. Montf. PYRULA perversa, Auct. and such other species as have an
angulated spire. Fig. 388.
FUSIFORM. (_Fusus_, a spindle.) Shaped like a spindle, swelling in the
centre and tapering at the extremities. _Ex._ Fusus, fig. 387.
FUSUS. Brug. (A spindle.) _Fam._ Canalifera, Lam. Siphonostomata,
Bl.--_Descr._ Fusiform, turrited, with many rounded whorls; aperture
generally oval, terminating in a long straight canal; operculum horny,
pyriform.--_Obs._ The Fusi are subject to considerable variations in
form. The recent species are numerous and do not appear to be confined
to any climate. The fossil species are also numerous, chiefly abounding
in the tertiary formations. The recent species are mostly tropical.
Fig. 387, F. Colus.
GALATHÆA. Brug. POTAMOPHILA, Sow. MEGADESMA, Bowd.
GALEA. Klein. PURPURA, Auct.
GALEOLARIA. Lam. (From Galea, a helmet or crest.) A genus composed of
species of SERPULA, Auct. Distinguished as being fixed by the side of
the shell, and having the anterior extremity erect, the aperture
terminating in a tongue-shaped projection.--_Obs._ This genus is said
by Lamarck to resemble Vermilia in other respects, but to differ in
having the anterior part raised. Fig. 6, G. decumbens. Africa and
Australia.
GALEOMMA. Turt. _Fam._ PHOLADARIA, Lam.--_Descr._ Thin, oval,
equivalve, equilateral, with the ventral margin gaping; hinge with one
cardinal tooth in each valve; muscular impressions two, approximate;
palleal impression interrupted, not sinuated; ligament small, partly
internal, partly external, fixed on a prominent fulcrum.--_Obs._ The
wide hiatus in the ventral margins of this equilateral shell prevents
the possibility of confounding it with any other. Four or five recent
species are known, one of which is found on the coast of Sicily, and
also in the British Channel. G. Turtoni, fig. 58.
GALERICULUS. (_Galericulum_, a little cap or bonnet.) VELUTINA, Auct.
fig. 337.
GALERUS. Humph. CALYPTRÆA, Lam.
GAPING. (_Hians._) Bivalve shells are said to gape when the margins do
not meet all round. _Ex._ Gastrochæna, fig. 52.
GARI. Schum. PSAMMOBIA, Lam.
GASTEROPODA. Lam. ([Greek: Gastêr], _gaster_, belly; [Greek: pous,
podos], _pus_, _podos_, a foot.) The second order of the class
Mollusca, Lam. containing those molluscous animals whose organs of
locomotion are ventral. Most of the shells belonging to this order are
patelliform, placed upon the back of the animals, which rest or crawl
upon the belly. This order is divided into Pneumonobranchiata, that is,
Comments (0)