Part 71

STORILLUS. Montf. 1, 131. A genus of microscopic Foraminifera, included in the genus Rotalites in M. De Blainville's system.

STRAPAROLLUS. Mont. A genus containing some species of HELIX, Auct. Generic characters not defined.

STREPTAXIS. Gray. Fam. Colimacea, Lam.--Descr. Ovate, or oblong; when young, sub-hemispherical, deeply umbilicated, with rapidly enlarging whorls. At length the penultimate whorl is bent towards the right and dorsal side of the axis, and the umbilicus becomes depressed, and often nearly closed. The mouth is lunulate, the edge slightly thickened and reflected, and often with a single tooth on the outer side of the inner lip.--Obs. This genus of land shells is separated from Helix on account of the eccentricity of the penultimate whorl. S. contusa, fig. 269.

STRIATED. (Stria, a groove.) Marked with fine grooves or lines.

STRIGOCEPHALUS. Defr. PENTAMERUS, Sow.? GYPIDIA, Dalman.

STROMBUS. Auct. Fam. Alatæ, Lam. Angiostomata, Bl.--Descr. Oblong, turrited, rather ventricose, solid; aperture generally lengthened, terminating posteriorly in a short canal, and anteriorly in an emargination or truncated canal; outer lip, when young, thin; when full grown, thickened and expanded, lobed at the spiral extremity, sinuated anteriorly near the caudal canal.--Obs. This well known genus includes some species of immense size, commonly called conch shells. Most of the recent species are brought from the Indian Ocean. Very few fossil species are known. The young shells have very much the appearance of cones, the outer lips being thin. There are also several species which do not, even when full grown, thicken their outer lips very considerably. The genus Strombus is distinguished from Rostellaria, by the notch in the outer lip, which in the latter genus is close to the canal. Fig. 406, S. pugilis.

STROPHOMENA. Rafinesque. ORTHIS, Dalman.

STROPHOSTOMA. Deshayes. A fossil shell, of the family of Colimacea, Lam. in some degree resembling Anostoma, having the aperture turned upwards towards the spire, it is, however, umbilicated, and is said to have an operculum resembling that of Cyclostoma. It is the Ferussina of Grateloup. Fig. 534, 5, 6.

STRUTHIOLARIA. Auct. (Struthio, an Ostrich.) Fam. Canalifera, Lam.--Descr. Oblong, turrited, thick; spire turrited, composed of several angulated whorls; aperture oval, sub-quadrate, oblique; outer lip thickened, reflected, advancing in the centre, receding towards the extremities; inner lip thickened, expanded over the columella and part of the body whorl.--Obs. This singular genus, consisting of three or four recent species, is named "Pied D'Autruche" by the French, on account of some resemblance in the outer lip to the foot of the Ostrich. From New Zealand. Fig. 391, S. straminea.

STYLIFER. Brod. (Stylus, a style; fero, to bear.)--Descr. Thin, pellucid, turbinated; apex a little out of the perpendicular; aperture wide anteriorly, gradually narrowing towards the spiral extremity, where it terminates acutely.--Obs. This is a genus of small, transparent shells, found burrowing in the rays of Starfish. There are but two or three species at present known, one of which is elongated like Terebra, the other nearly globular. Fig. 12, S. astericola. West Indies, Gallapagos, and Britain.

STYLINA. Flem. STYLIFER, Brod.

SUB. (under.) Used as a prefix and signifying nearly. Thus a bivalve-shell, the valves of which are nearly alike, would be described as sub-equivalve.

SUB-APLYSIACEA. Bl. The first family of the order Monopleurobranchiata, Bl. containing several genera of Mollusca without shells, and the genus Pleurobranchus.

SUB-BIVALVES. A term of distinction applied by De Blainville, to those spiral univalves which have an operculum; these, as they constitute two distinct pieces, he considers as forming a medium between univalves and bivalves.

SUB-MYTILACEA. Bl. The sixth family of the order Lamellibranchiata, Bl. the shells belonging to which are described as free, rather pearly, regular, equivalve; hinge dorsal, laminated; ligament external; two muscular impressions; palleal impression not sinuated. This family, with the exception of the last genus, agrees with the family Nayades of Lamarck, and contains the genera Anodon, Unio, and Cardita.

SUB-OSTRACEA. Bl. The second family of Lamellibranchiata, Bl. the shells of which are described as of a compact texture, sub-symmetrical; with the hinge rather complex; one single, sub-central, muscular impression, without any traces of palleal impression. This family corresponds with the Pectenides of Lamarck, and part of the genus Ostrea in the system of Linnæus. It contains the genera Spondylus, Plicatula, Hinnites, Pecten, Pedum, Lima.

SUB-SPIRAL. Not sufficiently spiral to form a complete volution.

SUBULA. Bl. (An awl.) A generic name under which M. De Blainville includes TEREBRA maculata, Auct. f. 428, together with nearly all the species of Terebra, enumerated by Lamarck and other authors; only leaving in the latter genus those species, which being more bulbous, or ventricose, nearly resemble Buccinum in general form. These last mentioned species, such as Terebra buccinoidea, (fig. 247) have been formed into a new genus by Mr. Gray, under the name Bullia. If both these genera were adopted, the genus Terebra would be extinct.

SUBULATE. (Subula, an awl.) A term applied to shells which are long and pointed as in Terebra. Fig. 427, 428.

SUCCINEA. Drap. (Succinum, amber.) Fam. Colimacea, Lam. Limacinea, Bl. Sub-genus, Cochlohydra, Fer.--Descr. Ovate, rather elongated; aperture large, entire, longitudinal; spire short; outer lip thin, continuous with the thin, sharp-edged columella; inner lip spread over a part of the body-whorl.--Obs. The shells belonging to this genus of partly amphibious mollusca, are distinguished from Limnæa by not having a fold on the columella The S. amphibia is of a bright amber colour. Fig. 265, 266. Temperate and tropical climates.

SULCATED. (SULCATUS, lat.) Having grooves or furrows.

SULCI. Grooves or furrows.

SUTURE. (Sutura, lat.) A seam, stitch, joining together. Applied particularly to the line which marks the joining of the whorls of the spire. The suture is distinguished as simple, as in most cases; or double, when accompanied by a parallel groove close to it; marginated, when produced into a ledge by the matter which fills up and covers it; obsolete, when it is filled up so as not to be visible, as in the case of Ancillaria.

SYLVICOLA. Humph. CYCLOSTOMA, Lam.

SYMMETRICAL, ([Greek: sun], syn, similar; [Greek: metron], metron, proportion.) Both sides alike. Although the term is used thus as one of distinction, it is to be observed that no shells are strictly and perfectly symmetrical; even in the Nautilus, the apex verges in a slight degree towards one side of the shell. Two kinds of univalve are symmetrical, or nearly so; 1st. Those which are symmetrically convolute, as the Nautilacea and the Ammonacea, which are spiral; 2nd. Those which are not spiral, but simply conical, as the patelliform shells. Bivalves belonging to the Brachiopoda are also symmetrical. Ex. Patella, fig. 229. Ammonites, fig. 478.

SYMPHYNOTA. Lea. A genus of Nayades, in which Mr. Lea proposed to include species of the genus UNIO, the valves of which are connate, or united at the dorsal margin. We believe that this distinction, as a genus, has been abandoned by its author. The fact is, that all the Uniones are Symphynotæ when in a young state. In Unio Alatus, (fig. 147) and Dipsas plicatus, (fig. 142) it will be observed that the valves have not separated at the dorsal edge, but are broken lower down.

TAPADA. (Gray. Turton. p. 127.) A division of the genus HELIX, containing HELIX aperta, Auct. or the Tapada snail.

TAPES. Schum. PULLASTRA. Sow.?