being attached by the whole length of their shell, give the idea of
creeping or crawling. _Ex._ Vermilia, fig. 7.
RETICULATED. (_Reticulatus._) Resembling net-work.
RETIFERA. Bl. The first family of the order Cervicobranchiata, Bl.
containing the genus Patella.
REVERSED or SINISTRAL SHELLS, are those in which the aperture is on the
left side of the shell, while it is held with the mouth downwards, and
towards the observer. _Ex._ Balea, fig. 296. Attached bivalves are said
to be reversed, when the left valve is free, instead of the right; a
circumstance which sometimes occurs in Chama and Ostrea.
RHEDA. Humph. HYALÆA, Lam.
RHINOCLAVIS. Sw. A genus of "Cerithinæ," Sw. thus described: "channel
curved backwards, in an erect position; inner lip very thick, with a
tumid margin; pillar generally with a central plait; operculum
ear-shaped; lineatum. En. M. 443, fig. 3, Vertagus. Ib. f. 2,
subulatum. Lam. No. 23, fasciatum. Mart. 157, f. 1481. obeliscus, En.
Méth. 443, f. 4; aluco, Ib. f. 5, (Aberrant,) semi-granosum. Ib. 443,
f. 1, asperum. Mart. 157, f. 1483."
RHINOCURUS. Montf. A genus of microscopic Foraminifera.
RHINODOMUS. Sw. A genus of "Scolyminæ," Sw. thus described: No internal
groove; shell clavate; the spire longer than, or equal with the
aperture; the whorls with ridges or longitudinal varices, and rendered
hispid by transverse grooves; inner lip wanting; pillar with a terminal
fold; aperture striated; outer lip with a basal sinus. R. senticosus,
Chem. tab. 193. f. 1864-1866.
RHIZORUS. Montf. A genus described from a microscopic shell, appearing
to be a cylindrical Bulla.
RHODOSTOMA. Sw. A sub-genus of "Turbininæ," Sw. p. 344.
RHOMBOIDAL. ([Greek: rhomboeidos], _rhomboeidus_.) Having a rhombic
form, i. e. four-sided; two sides meeting at acute, two at obtuse,
angles. Conchologists are not very strict in the application of this
term, for, indeed, a perfect rhomboidal figure could not be found among
all the testaceous productions of the sea.
RHOMBOIDES. Bl. A genus described as resembling Byssomya in the shell,
but differing in the animal. MYTILUS rugosus, Gmelin. HYPOGÆA barbata,
Poli.
RHOMBUS. Montf. ([Greek: rhombos], _rhombos_, a rhomb.) A genus
consisting of species of CONUS, having a rhomboidal or quadrilateral
form and a coronated spire. _Ex._ Conus nocturnus, fig. 459.
RICINULA. Lam. (Resembling the seed-vessel of the _Ricinus_.) _Fam._
Purpurifera, Lam. Entomostomata, Bl.--_Descr._ Sub-ovate, thick,
tuberculated; spire short; aperture narrow, terminating anteriorly in a
short canal; outer-lip thickened, denticulated within, digitated
without; columellar lip spread over a portion of the body whorl, and
granulated.--_Obs._ This interesting genus is composed of some neat
little shells allied to Purpura, from which they are distinguished by
the finger-like branching of the outer lip, and the granulations of the
columella. Fig. 413, R. Horrida.
RIGHT. See DEXTRAL.
RIMULA. Defr. A genus consisting of a minute species of EMARGINULA,
Auct. which has a fissure near the margin, but not reaching it. R.
Blainvillii, fig. 243.
RIMULINA. D'Orbigny. A genus of microscopic Foraminifera.
RINGICULA. Deshayes. A genus founded on Auricula ringens of Lamarck and
several small fossils, resembling in some respects Pedipes of Adanson;
they would belong to Tornatella, were it not for the lips being
thickened and marginated, fig. 540, A. ringens.
RISSOA. Freminville. _Fam._ Ellipsostomata, Bl. Melaniana,
Lam.--_Descr._ Oblong, turrited, acuminated; spire long, consisting of
numerous whorls; aperture round or oval, pointed posteriorly, dilated
anteriorly; outer lip slightly thickened, emarginated, operculum
horny.--_Obs._ The Rissoæ are small white, marine shells, considered by
some authors as resembling Melaniæ, but placed by Sowerby near the
Scalariæ. They are principally from the shores of the Mediterranean,
and are also very abundant on the British shores, as well as the East
and West Indian. Fig. 346, R. reticulata.
ROBULUS. Montf. A genus of microscopic Foraminifera.
ROLLUS. Montf. A genus composed of CONUS Geographus, Auct. fig. 462,
and other species, rather cylindrical in form, and having a coronated
spire.
ROSALINA. D'Orb. A genus of microscopic Foraminifera.
ROSTELLARIA. (From _rostrum_, a beak.) _Fam._ Alatæ, Lam.
Siphonostomata, Bl.--_Descr._ Turrited, fusiform, thick, smooth or
ribbed; aperture oval, terminating anteriorly in a long canal,
posteriorly in a channel running up the spire; outer lip dilated,
thickened, sometimes digitated, running up all or part of the spire,
with a sinus near the anterior canal; inner lip smooth, spread over
part of the body whorl and of the spire. The Red Sea and the Indian
Ocean produce the few known species of this genus.--_Obs._ HIPPOCHRENES
is the name given by De Montfort, to those fossil species which have
the outer lip simple and very much dilated. R. curvirostrum, fig. 412.
APORRHAIS is a name given to another proposed genus, composed of
Rostellaria pes-pelecani, Auct. fig. 404. and similar species.
ROSTRATED. (From _rostrum_, a beak.) Having one or more protruding
points, as Tellina rostrata.
ROTALIA. Lam. A genus of microscopic Foraminifera. The same as
Rotalites of De Montfort.
ROTELLA. Lam. (_A little wheel._) _Fam._ Turbinacea, Lam.--_Descr._
Orbicular, generally smooth, shining; spire conical, depressed, short;
aperture subtrigonal; outer lip thin, angulated near the centre; inner
lip spread over the surface of the whorls, forming a thickened disc.
Operculum horny, orbicular, spiral, with numerous whorls.--_Obs._ The
pretty little shells thus described are found in seas of tropical
climates. They are distinguished from other genera of the family by
their lenticular form and the orbicular callosity of the under surface.
Fig. 357, R. vestiaria.
RUDISTES. Lam. A family of the order Conchifera Monomyaria, Lam. the
shells of which are described as irregular, very inequivalve, without
distinct umbones; the ligament, hinge and animal entirely unknown. The
shells contained in this family may be thus distinguished.
1. CALCEOLA. Large valve conical; attached by a flat space between
the umbones, which form the extremities of the shell. Fig. 194.
2. HIPPURITES. Large valve cylindrical, with two internal lobes or
varices. Fig. 198.
3. SPHÆRULITES. Large valve attached, including _Radiolites_.
Birostrites is proved to be the cast of a Sphærulites. Fig. 193,
196.
4. HIPPONYX. Flat valve attached, upper valve conical. Fig. 199,
200.
RUDISTES. Bl. The second order of the class Acephalophora, Bl.
containing the genera Sphærulites, Crania, Hippurites, Radiolites,
Birostrites and Calceola.
RUDOLPHUS. Lam. MONOCEROS, Auct.
RUFOUS. Reddish brown.
RUGOSE. Rough, rugged.
RUPELLARIA. Fl. de Belvue. An unfigured shell placed by De Blainville
in a division of the genus Venerirupis.
RUPICOLA. Fl. de Belvue. A shell described by De Blainville as an
equivalve, terebrating species of ANATINA. A. rupicola, Lam.
SABINEA. A genus of shells resembling small species of LITTORINA, as L.
Ulvæ, &c. of our shores.
SADDLE OYSTER. PLACUNA Sella, so called on account of a resemblance in
shape to a saddle; the part near the umbones being flat, and the
ventral margins being turned up in a sort of fluting or peak.
SAGITTA. (_An arrow._) An ancient name for Belemnites.
SALIENT. (_Saliens._) Jutting out, prominent.
SALPACEA. Bl. The second family of the order Heterobranchiata, Bl.
containing no genera of shells.
SANDALINA. Schum. CREPIDULINA, Lam. A genus of microscopic
Foraminifera.
SANGUINOLARIA. Lam. (_Sanguis_, blood.) _Fam._ Nymphacea, Lam.
Pyloridea, Bl.--_Descr._ Equivalve, inequilateral, transverse,
sub-ovate, rounded anteriorly, sub-rostrate posteriorly, compressed,
thin, covered with a shining epidermis, gaping at the sides; hinge with
two cardinal teeth in each valve, and an external ligament supported
upon a prominent fulcrum; muscular impressions two in each valve,
lateral, irregular, palleal impressions with a large sinus.--_Obs._
This description is made to exclude some of Lamarck's species of
Sanguinolaria, such as S. occidens, S. rugosa, which are Psammobiæ; and
to include others which he has left out. The Sanguinolariæ are
sub-rostrated posteriorly, while the Psammobiæ are sub-quadrate and
have a posterior angle. Fig. 98, S. rosea. Sandy shores of tropical
climates.
SARACENARIA. Defr. A genus of microscopic Foraminifera.
SAVIGNIUM. Leach. A genus of Sessile Cirripedes, described as composed
of four valves soldered together, and a convex bivalve operculum; the
ventral and posterior valve on each side being soldered together, in
other respects resembling PYRGOMA. Fig. 30.
SAXICAVA. Fl. de Belvue. Journ. de Ph. an. 10. (_Saxum_, a stone;
_cava_, a hollow.) _Fam._ Lithophagidæ, Lam. Pyloridea, Bl.--_Descr._
Transverse, irregular, generally oblong, inequilateral, sub-equivalve,
gaping anteriorly; ligament external; muscular impressions two,
lateral; palleal impression interrupted, not sinuated; hinge, when
young with sometimes two or three minute, obtuse, generally indistinct,
cardinal teeth; which become obsolete when full grown.--_Obs._ Several
genera have been founded only upon the difference between the young and
old shell of the same species of this genus. The Saxicavæ are found in
the little hollows of rocks; in cavities on the backs of oysters, of
roots of sea-weeds, &c. in northern and temperate climates. S. rugosa,
fig. 94.
SCABRICULA. Sw. A sub-genus of Mitræ, consisting of species which have
a roughened external surface, &c. Sw. Malac. p. 319.
SCABROUS. Rough.
SCALA. Klein. SCALARIA, Auct.
SCALARIA. Auct. _Fam._ Scalariana, Lam. Cricostomata, Bl.--_Descr._
Turrited, oval or oblong; spire long, composed of rounded, sometimes
separate whorls, surrounded by regular concentric ribs; aperture oval,
peristome reflected continuous, entire.--_Obs._ The typical species of
this genus, commonly called the Wentletrap, (S. pretiosa) is celebrated
for the beautiful appearance caused by the numerous ribs encircling the
whorls, and formerly produced an immense price in the market. It is
brought from China. There are many smaller species, some of which are
equally elegant. Fig. 351, S. Pallasii, Kiener.
SCALARIANA. Lam. A family belonging to the first section of the order
Trachelipoda, Lam. The shells belonging to it are described as having
the inner and outer lips continuous, without a canal, emargination, or
other division. In this respect the family is stated to differ from the
Turbinacea, and is therefore separated. The genera may be distinguished
as follows:--
1. VERMETUS. Irregularly twisted, like Serpula. Fig. 345.
2. EULIMA. Pyramidal; apex contorted; including _Bonellia_. Fig.
347, 348.
3. RISSOA. Pyramidal, straight, consisting of few whorls. Fig. 346.
4. SCALARIA. With external varices. Fig. 351.
5. CIRRUS. Trochiform. Fig. 349.
6. ENOMPHALUS. Orbicular. Fig. 350.
7. DELPHINULA. Few whorls, rapidly increasing. Fig. 352.
SCALLOP. The common name for shells of the genus Pecten, the larger
species of which were worn by pilgrims to the Holy Land in the time of
the Crusades.
SCALPELLUM. Leach. (A little knife or lancet.) _Order_, Pedunculated
Cirripedes, Lam.--_Descr._ Flat, quadrated, acuminated, composed of
thirteen valves, one dorsal, arcuated; one pair apicial, acuminated;
one pair ventral; two pair lateral, small, sub-quadrate; pedicle
scaly.--_Obs._ This genus and _Smilium_, are the only Pedunculated
Cirripedes which have thirteen valves; in the latter genus, which we
think should at any rate be united to this, the valves are somewhat
differently placed, and the pedicle is said to be smooth. Fig. 35,
Scalpellum vulgare. British.
SCAPHA. Klein. (_A boat._) NAVICELLA, Auct.
SCAPHANDER. Montf. BULLA lignaria, Auct. Fig. 251.
SCAPHELLA. Sw. A genus of the family "Volutinæ," Sw. thus described:
"Shell smooth, almost polished; outer lip thickened internally; suture
enamelled; lower plaits the smallest; apex of the spire various: 1.
fusiformis. Sw. Bligh. Cat. 2. undulatus. _Ex._ Conch. pl. 27. 3.
Junonia, _Ex._ Conch. pl. 33. 4. stromboides. 5. papillosa. Sw. Sow.
gen." Sw. Malac. p. 318.
SCAPHITES. (_A boat._) _Fam._ Ammonacea, Lam. and Bl.--_Descr._
Convolute, chambered, closely related to the Ammonites, from which it
differs in the last whorl being eccentrically straightened, and
lengthened, and again incurved towards the extremity. Only known in a
fossil state. Fig. 481, S. æqualis.
SCAPHULA. Sw. A genus of "OLIVINÆ," Sw. thus described: "Spire very
short, thick, obtuse, and not defined; aperture very wide, with only
two or three oblique plaits at the base. Sw. patula, _Sow._ Tank. Cat.
2331. (_b._)" (Sw. p. 322.)
SCARABUS. Montf. (_Scarabæus_, a kind of beetle.) _Fam._ Colimacea,
Lam. Auriculacea, Fer.--_Descr._ Oval, somewhat compressed, smooth,
with slightly raised varices; spire equal in length to the aperture,
pointed, consisting of numerous whorls; aperture ovate, rounded
anteriorly, pointed posteriorly, modified by the last whorl; outer lip
sub-reflected, with several prominent folds on the inner edge; inner
lip spread over a portion of the body whorls, with several prominent
folds.--_Obs._ The shells of this genus are found like Auriculæ, in
marshy places. C. imbrium is said to have been found on the tops of
mountains, by Captain Freycinet. Fig. 299*, S. imbrium.
SCHIZODESMA. Gray. A genus composed of species of MACTRA, Auct. with
the ligament placed in an external slit. Fig. 8, M. Spengleri.
SCISSURELLA. D'Orbigny. (_Scissus_, cut.) _Fam._ Turbinacea,
Lam.--_Descr._ Sub-globose, umbilicated, with a spiral groove
terminating at the margin of the outer lip in a slit; spire short;
aperture oval, modified by the last whorl; outer lip sharp, with a deep
slit near the spire. Recent on the coasts of Britain; fossil in the
Calcaire-grossièr.--_Obs._ This genus, consisting of small shells, is
known from Pleurotomaria by the shortness of the spire; the latter
genus being trochiform. Fig. 340, S. elatior.
SCOLYMUS. Sw. A genus of the family "Scolyminæ." Sw. (Turbinella) thus
described: "Sub-fusiform, armed with foliated spines; spire shorter;
pillar with distinct plaits in the middle." The species enumerated are,
"cornigerus, pugillaris, Globulus, Rhinoceros, ceramicus, Capitellum,
umbilicaris, mitis." Sw. Malac. p. 304.
SCORTIMUS. Montf. A genus of microscopic Foraminifera.
SCROBICULARIA. Schum. Species of LUTRARIA, Act. of a rounded shape.
LIGULA, Leach.
SCROBICULATED. (_Scrobiculus_, a little ditch or furrow.) Having small
ditches or furrows marked on the surface.
SCUTELLA. Brod. (_Scutellum_, a little shield.) _Fam._ Phyllidiana,
Lam.--_Descr._ Shaped like Ancylus, pearly within; apex posteriorly
inclined, central, involute; muscular impressions two, oblong, ovate,
lateral; aperture large, ovate.--_Obs._ This genus is intermediate
between Ancylus and Patella; while in the aspect of the beak, the
observer is reminded of Navicella.
SCUTIBRANCHIATA. Bl. (_Scutum_, a shield; _branchiæ_, gills.) The third
order of Paracephalophora Hermaphrodita, Bl. containing animals with
patelliform, but not symmetrical shells, and divided into the families
Otidea and Calyptracea.
SCUTUM. Montf. (_A shield._) PARMOPHORUS ELONGATUS, Lam.
SECURIFORM. (_Securis_, an axe; _forma_, shape.) Hatchet-shaped. _Ex._
Pedum, fig. 179.
SEDENTARY ANNELIDES. Lam. The third order of the class Annelides, Lam.
distinguished from the two other orders by the circumstance of the
animal being enveloped by a shelly tube which it never entirely leaves.
The order is divided into the families Dorsalia, Maldania, Serpulacea,
and Amphitrites. Fig. 1 to 13.
SEA DATE. The common name for PHOLAS Dactylus in the market, given to
it on account of its cylindrical shape. Fig. 35.
SEGMENTINA. Flem. NAUTILUS Lacustris, Montagu. Test. Brit. Planorbis
nitidus, Drap. tab. 2. Fig. 17 to 19.
SEMICORDATE. Half heart-shaped.
SEMIDISCOIDAL. Forming the half of a circular disc.
SEMILUNAR. Half moon-shaped.
SENECTUS. Humph. A genus of "Senectinæ," thus described by Swainson:
"Imperforate; the base produced into a broad flat lobe, spire rather
elevated and pointed; the whorls convex; aperture perfectly round; not
more oblique than _Helix_; inner lip entirely wanting, imperialis.
Mart. 180. f. 1790. marmoratus. l. M. 448. f. 1." Sw. p. 348.
SEMIPHYLLIDIANA. Lam. The second family of the order Gasteropoda, Lam.
the genera of which are distinguished as follows:--
1. UMBRELLA, round, flat; apex central, muscular impression not
interrupted. Fig. 233.
2. PLEUROBRANCHUS, apex lateral, sub-spiral. Fig. 232.
SENOCLITA. Schum. CINERAS, Leach.
SEPTARIA. Lam. See TEREDO.
SEPTUM. (Lat.) An enclosure, applied to the thin plate of Crepidula,
fig. 239; also to the plates dividing the chambers of multilocular
shells.
SERAPHS. Montf. TEREBELLUM convolutum, Lam. Fig. 451.
SERPULA. Auct. (_A little serpent._) _Fam._ Surpulacea, Lam.--_Descr._
Tubular, narrow, pointed at the apex, gradually widening towards the
aperture, attached irregularly, sometimes spirally, twisted,
imbricated; keeled or plain; aperture generally round, with the edge
simple, or angulated by the termination of external ribs or
keels.--_Obs._ This description is intended to include the genera
Serpula, Spirorbis, Vermilia, Galeolaria, &c. The Serpulæ abound in all
seas, on rocky shores, at any time covered by water, attached to any
kind of marine substance, whether moveable or stationary. The fossil
species occur in almost all tertiary strata. Fig. 4 to 7.
SERPULACEA. Lam. The fourth family of the order Sedentary Annelides,
Lam. containing the following genera of tubular, irregular shells.
1. SERPULA, attached by a small portion of the shell. Fig. 4.
2. SPIRORBIS, attached by the whole length, coiled. Fig. 5.
3. Galeolaria, with the open extremity raised, and the aperture
tongue-shaped. Fig. 6.
4. VERMILIA, attached by the whole length, straight or waved. Fig.
7.
5. SPIROGLYPHUS, which hollows a bed in the body to which it is
attached. Fig. 8.
Sowerby. (Genera of Shells, published at 50, Great Russell
Street, Bloomsbury,) gives satisfactory reasons for re-uniting the
whole of the preceding under the name SERPULA.
6. MAGILUS, which burrows in coral; outer lip reflected. Fig. 9 to
10.
7. LEPTOCONCHUS, outer lip reflected. Fig. 11.
8. STYLIFER, spiral, thin, globular, living in Starfish. Fig. 12,
13.
The three last genera should certainly find some other place in
the system.
SESSILE CIRRIPEDES. Lam. (_Sessilis_, low, dwarfish.) An order of
Cirripedes, consisting of those which are attached by the base of the
shells, containing the genera Tubicinella, Balanus, Coronula, Acasta,
Pyrgoma, Creusia. To which may be added some other genera enumerated in
explanation of figures 14 to 33. The shells of the Sessile Cirripedes
consist of two different sets of valves: 1st. The _parietal_ valves, or
pieces arranged in a circle, side by side, around the body of the
animal, (an arrangement designated _coronular_ by De Blainville.) 2nd.
The _opercular_ valves, or pieces placed so as to enclose the aperture.
Between those opercular valves the ciliæ protrude which characterize
the class. Besides these two sets of valves, there is generally a
shelly plate, serving as a sort of foundation to the rest. The Sessile
Cirripedes may be thus arranged.
1. TUBICINELLA. Six parietal valves, tube-shaped, opercular valves
perpendicular. Fig. 14.
2. CORONULA. Six parietal valves, opercular valves horizontal. Fig.
15, 16, 17, 18.
These two genera fix themselves in the skin of the Whale. The
latter has been divided into the genera Chelonobia, Cetopirus,
Diadema, and Chthalamus.
3. PLATYLEPAS. Valves divided, each having a prominent internal
plate. Fig. 19.
4. CLITIA. Parietal valves four, opercular valves two, valves
dove-tailed into each other. Fig. 20.
5. ELMINEUS. Parietal valves four, opercular valves four. Fig. 22.
6. CONIA. Parietal valves four, thick and porous at the base. Fig.
21.
7. OCTOMERIS. Parietal valves eight. Fig. 24.
8. CATOPHRAGMUS. Parietal valves numerous, irregular. Fig. 23.
9. BALANUS. Parietal valves six; opercular valves four, placed
against each other conically in pairs. This genus has been divided
into Acasta, Conoplea, Chirona, and Balanus. Fig. 25, 26, 27.
10. CREUSIA. Parietal valves four, supported on the edge of a
funnel-shaped cavity. Fig. 28.
11. PYRGOMA. Paries simple, supported on a cavity. This genus has
been divided into the genera Nobia, Savignium, Pyrgoma, Adna,
Megatrema, and Daracia. Fig. 29 to 33.
SETIFEROUS. Hairy.
SHANK SHELL. The vulgar name for the shell designated Murex Rapa. It is
used in Ceylon for ornamental purposes.
SIDEROLITES. Montf. A genus of microscopic Foraminifera.
SIGARETUS. Lam. _Fam._ Macrostomata, Lam.--_Descr._ Suborbicular,
oblique, haliotoid, thick; spire depressed, consisting of two or three
rapidly increasing whorls; aperture wide, entire, modified by the last
whorl, the width exceeding the length; columella tortuous; inner lip
spread thinly over part of the body whorl; epidermis thin.--_Obs._ This
genus is distinguished from Natica, by the width of the aperture, and
the absence of the umbilical callosity. It may be known from Stomatia,
and Stomatella, by the texture, which in Sigaretus, is never pearly as
in Stomatia, the former being partly an internal shell. Fig. 334, S.
concavus. Mostly brought from tropical climates.
SILIQUA. Megerle. (A husk, or pod.) LEGUMINARIA, Schum. A genus
composed of species of SOLEN, Auct. which have an internal rib. Fig.
51, Solen radiatus.
SILIQUARIA. Brug. _Fam._ Cricostomata, Bl. Dorsalia, Lam.--_Descr._
Tubular, rugose, spiral near the apex, irregularly twisted near the
aperture, with a longitudinal fissure radiating from the apex, and
proceeding through all the whorls and sinuosities of the tube.--_Obs._
This genus was included in Serpula by Linnæus, from which, however, it
is distinguished by the longitudinal slit, fig. 1. S. anguina. The
recent species are found in the sponges with siliceous spiculæ, in the
Mediterranean; the fossils in tertiary beds.
SIMPLE. (_Simplex_, lat.) Single, entire, uninterrupted, undivided.
SIMPLEGAS. Mont. 1, 83. (_Simplex_, simple; [Greek: gastêr], _gaster_,
belly.) A genus described by De Blainville, as being discoidal, and
having the spire uncovered like AMMONITES, but having the chambers
divided, by simple septa, like Nautilus.--_Obs._ The septa of the shell
named Simplegas by De Montfort, are evidently sinuous, according to his
figure. Fig. 475, S. sulcata.
SINISTRAL. (_Sinister_, left.) On the left side. A sinistral shell is a
_reversed_ one. The sinistral valve of a bivalve shell may be known, by
placing the shell, with its ligamentary or posterior part towards the
observer; the sides of the shell will then correspond with his right
and left side.
SINUOUS. Winding, serpentine. The septa of Ammonites are sinuous. The
muscular impression of the mantle, or palleal impression of some
bivalve shells, is sinuated near the posterior muscular impression.
SINUS. (_Sinus_, a winding, or bay.) A winding or tortuous excavation.
The sinus in the outer lip of Strombus, fig. 406; and that in the
muscular impression of Venus, will be indicated by the letter _s_.
SIPHON. ([Greek: Siphon], siphon.) A pipe, or tube. A shelly tube
passing through the septa of chambered shells. It is said to be
_dorsal_, _central_, or _ventral_, according to its situation near the
outer, or inner parts of the whorl. See Introduction.