Part 72

TECTUS. Montf. A genus composed of species of the genus Trochus, having elevated, conical spires, and columella notched or truncated by a spiral fold. Fig. 359. Trochus maculatus, presents an example.

TELEBOIS. Montf. A genus of microscopic Foraminifera.

TELESCOPIUM. Montf. CERITHIUM Telescopium, Auct. fig. 378.

TELLINA. Linn. Fam. Nymphacea, Lam. Conchacea, Bl.--Descr. Sub-equivalve, inequilateral, compressed, rounded anteriorly, slightly beaked or angulated posteriorly, the posterior ventral margin having a flexuosity; hinge with two cardinal and generally two lateral teeth in each valve; muscular impressions, two in each valve, remote; palleal impression with a large sinus.--Obs. The fold or bending in the posterior margin distinguishes this genus from others which it nearly resembles. It is composed of some bivalves of great beauty and variety, which are found in nearly all climates. Fig. 105, T. radiata, 106, T. lingua-felis.

TELLINIDES. Lam. Fam. Nymphacea, Lam.--Descr. Sub-equivalve, inequilateral, transverse, compressed, rounded anteriorly, slightly beaked or angulated posteriorly; hinge with two cardinal teeth in each valve, and one lateral tooth in one valve, very near the cardinal teeth. Muscular impressions two, distant, palleal impression with a large sinus. Obs. This genus is distinguished from Tellina in having but one lateral tooth near the cardinal teeth. Fig. 107, T. rosea. Tropical.

TENUIPEDES. (Tenuis, slender; pedes, feet.) The second section of the order Conchifera Dimyaria, divided into the families Mactracea, Corbulacea, Lithophagidæ, Nymphacea.

TERACLITA. Schum. CONIA, Auct.

TEREBELLUM. Lam. (Terebra, an augur?) Fam. Convolutæ, Lam. Angyostomata, Bl.--Descr. Smooth, slender, oblong, sub-cylindrical; spire obtuse, short, sometimes hidden; (Seraphs, Montf.) aperture long, narrow posteriorly, wider anteriorly; outer lip slightly thickened, truncated, unconnected at the base with the columella; inner lip thin, smooth, nearly straight, spread over a portion of the body-whorl, continued in a ridge above the sutures of the spire.--Obs. Montfort has separated the fossil species with hidden spires, under the name Seraphs. (T. convolutum, Lam.) Only one recent species is known, of which there are several varieties, one spotted, one marked in sub-spiral lines, another in patches. It is brought from the East Indies. Fig. 451, T. convolutum; 452, T. subulatum.

TEREBRA. (An augur, a piercer.) Fam. Purpurifera, Lam. Entomostomata, Bl.--Descr. Subulate, elongated, pointed, turrited; spire long, consisting of numerous whorls; aperture small terminating in a short, reflected canal; outer lip thin; columella tortuous; operculum horny. The recent species are mostly tropical.--Obs. Nearly all the species enumerated by Lamarck and other authors are included by De Blainville in his genus Subula; those few species which that conchologist left in the present genus, being shorter and more ventricose than the others, approximate in shape to some of the Buccina, and are distinguished by Mr. Gray under the generic name Bullia. It seems strange, that De Blainville, being convinced of the necessity of separating the two groups, and consequently applying a new generic term to one of them, should have given that term to the larger number and the more typical species of the Lamarckian genus. Fig. 427, Bullia vittata. (Terebra.) Fig. 428, Terebra maculata. (Subula.)

TEREBRALIA. Sw. A genus of "Cerithinæ," Sw. thus described: "Outer lip much dilated, generally uniting at its base to the inner lip; leaving a round perforation at the base of the pillar; channel truncate; operculum round: palustre. Mart. f. 1472." Sw. p. 315.

TEREBRATING SHELLS. (Terebro, to pierce.) Shells which reside in holes pierced in rocks, wood, &c. by means of some corrosive secretion of the animal. Ex. Pholas, Teredo, &c.

TEREBRATULA. Brug. (Terebrans, bored.) Fam. Brachiopoda, Lam.--Order. Palliobranchiata, Bl.--Descr. Inequivalve, equilateral, oval or sub-trigonal, ventricose or compressed, attached by a tendon passing through an opening in the dorsal, or upper and larger valve, the umbo of which advances beyond that of the other valve; hinge destitute of a ligament, with two teeth in the dorsal valve, locked into corresponding cavities in the ventral, or lower valve, and with two curious processes originating at the umbo of the lower valve, presenting, in some species, the appearance of fine winding tape, advancing towards the front of the valve, and again receding to the centre, where the ends unite; muscular impressions two, placed near the centre of each valve.--Obs. The Terebratulæ are included in the genus Anomia in the system of Linnæus. The recent species are not very numerous--they are found in all climates. The fossil species are more numerous than the recent ones, occurring in the secondary and tertiary formations. T. Psittacea, fig. 202.

TEREDINA. (From Teredo.) Fam. Tubicolæ, Lam. Adesmacea, Bl.--Descr. Valves equal, inequilateral, with prominent umbones, as it were soldered to the outside of the rounded end of a shelly tube, of which they form a part; aperture of the tube partly divided; a flat accessary valve placed on the umbones.--Obs. This genus, which is only known in a fossil state, is distinguished from Teredo, by the valves being fixed on the tube, and the tube being closed at one extremity. Fig. 46, 47, T. personata.

TEREDO. Auct. (A piercer.) Fam. Tubicolæ, Lam. Adesmacea, Bl.--Descr. Valves equal, inequilateral; presenting when closed, an orbicular figure, with a large angular opening in front, and a rounded opening at the back; placed at the anterior extremity of an irregular, flexuous, elongated tube, open at both ends; the anterior termination divided in a double aperture opened and closed at the will of the animal by two opercula.--Obs. This genus of Molluscous Animals, is remarkable for boring holes in wood, which are filled by their elongated tubes, and give it a honey-comb appearance. Fig. 48. T. Navalis. Fig. 49, a piece of bored wood.

TERMINAL. When the umbones of a bivalve shell are placed at or near the extremity, as in Mytilus, fig. 158, Pinna, fig. 162, they are said to be terminal. The same term is also applied to the nucleus of an operculum, when it forms an extreme point, or is close to one of the edges.

TESSELLATED. (Wrought in chequer-work). A term applied to the colouring of shells, when arranged in regular defined patches like a tessellated pavement.

TESTACELLA. (Testa, a shell.) Fam. Limacinea, Lam. and Bl.--Descr. Haliotoid, compressed; aperture wide, oblique; columella flat, oblique; spire short, flat, consisting of less than two whorls.--Obs. This shell which is extremely small compared with the animal, is placed upon its back, near the posterior extremity. The animal is found in some of our gardens, and very much resembles the common garden slug. Fig. 261, T. Haliotoidea.

TESTACEOUS. (Testa, a shell.) Shelly. Testaceous Mollusca, are soft animals having shells. A testaceous operculum is one composed of shelly matter.

TETRACERA. Bl. The first family of the order Polybranchiata, Bl. containing no genera of testaceous mollusca.

TEXTILIA. Sw. A sub-genus of Conus, consisting of Conus bullatus, &c. Sw. Malac. p. 312.

TEXTULARIA. Defr. A genus of microscopic Foraminifera.

THALAMUS. Montf. A genus described as resembling Conilites, but curved and granulated.

THALLEPUS. Sw. A genus of "Aplysianiæ," Sw. thus described: "Body more slender and fusiform;" (than Aplysia,) "the lobes of the mantle short, and incapable of being used for swimming; tentacula two, large, ear shaped; eyes not visible. T. ornatus, Sw. Sp. Nov." Sw. p. 359.

THALLICERA. Sw. A generic name under which Swainson distinguishes AMPULLARIA Avellana, Auct.

THECIDIUM. (Thecas, a box.) Fam. Brachiopoda, Lam. Order, Palliobranchiata, Bl.--Descr. Lower valve concave, sub-trigonal, with the umbo produced into a triangular, slightly incurved beak, and with two short, pointed processes advancing from beneath the umbones; upper valve flat, rounded square, with a short, blunt appendage, formed to fit between the tooth-like process of the other valve; its inner surface ornamented with symmetrically curved ridges.

THECOSOMATA. Bl. The first family of the order Aporobranchiata, Bl. containing the genera Hyalæa, Cleodora, Cymbulia, Pyrgo.

THELICONUS. Sw. A sub-genus of Conus. Lardn. Cyclop. Malac. p. 312.

THELIDOMUS. Sw. A generic name under which Swainson has described a division of the genus Helix, and which he has also used to designate a genus in the family of "Rotellinæ," founded upon an aggregate of loose particles collected and agglutinated in a spiral form by the larva of an insect. Sw. Malac. p. 330 and 353.