Part 25

6. TROCHUS. Top-shaped; mouth generally angulated; operculum horny, consisting of many whorls; including _Elenchus_. Fig. 358, 359, 361.

7. MARGARITA. Operculum horny, consisting of few whorls; pearly. Fig. 362.

8. LITTORINA. Similar, not pearly; including _Assiminnea_. Fig. 363, 363*.

9. PHORUS. Attaching dead shells, stones, &c. Fig. 360.

10. MONODONTA or ODONTIS. A notch and prominent point at the lower part of the aperture. Fig. 366.

11. LACUNA. With an umbilicus. Fig. 364.

12. TURRITELLA. Elongated, screw-shaped. Fig. 369 to 371.

TURBINATED. (_Turbo_, a top,) Top-shaped. The term is applied generally to those shells which are large at one extremity, and narrow to a point at the other. _Ex._ Trochus, fig. 358; Turbinellus, fig. 382.

TURBINELLUS. Auct. (_A little top._) _Fam._ Canalifera, Lam. Siphonostomata, Bl.--_Descr._ Turbinated, thick, wide near the apex, generally tuberculated; spire short, depressed, mammillated; aperture rather narrow, terminating anteriorly in an open canal; outer lip thickened within; columella having from three to five prominent, compressed, transverse folds. The species of this genus are mostly tropical.--_Obs._ The Turbinelli are a well marked genus of marine shells, the species of which are numerous. No fossil species are known. The genus Cancellaria makes the nearest approach to Turbinellus in some characters, but may be distinguished by the roundness of its form, the raised lines inside the outer lip, and the obliquity of the folds on the columella. Fig. 382 to 384.

TURBO. Auct. (_A top._) _Fam._ Cricostomata, Bl. Turbinacea, Lam.--_Descr._ Turbinated, solid, ventricose, generally grooved or tuberculated; spire short, pointed; aperture generally rounded, sub-effuse anteriorly, entire; operculum shelly, solid, incrassated on the outer side, horny and sub-spiral on the inner side. The Turbines are mostly tropical.--_Obs._ The only certain means of distinguishing this extensive genus of marine shells from Trochus, is the operculum, which in the latter genus is horny, spiral, and composed of a great number of whorls. The Trochi, however, are in general more conical, and flatter at the under side of the whorls, and this constitutes Lamarck's distinction between the genera. T. setosus, fig. 368.

TURGID. (_Turgidus._) Puffed up, swollen, inflated. This term is applied synonymously with Ventricose.

TURRICULA. Humph. MELANIA, Auct.

TURRICULACEA. Bl. The seventh family of the Order Polythalamacea, Bl. containing the genus Turrilites, fig. 483.

TURRILITES. Lam. (_Turris_, a tower; [Greek: lithos], a stone.) _Fam._ Turriculacea, Lam. Ammonacea, Bl.--_Descr._ Chambered, turrited, spiral; septa sinuous and lobate, perforated by a siphon; aperture rounded, with the outer lip expanded. This genus, which is distinguished from the other Ammonacea by having the spire produced, _i. e._ not being convolute, consists of several species, occurring only in chalk-marl. Fig. 483.

TURRIS. Montf. A genus composed of those species of MITRA, Auct. which have the whorls angulated, with the aperture lengthened and undulated.

TURRITED. The spire of an univalve shell is said to be _turrited_ when the whorls of which it is composed are regulated so as to have the appearance of little turrets rising above each other, as in Mitra, fig. 431.

TURRITELLA. Lam. (_A little tower._) _Fam._ Turbinacea, Lam. Cricostomata, Bl.--_Descr._ Turrited, elongated, generally grooved spirally; spire pointed, consisting of numerous whorls; aperture rounded or angulated; inner and outer lips thin, confluent anteriorly; operculum horny.--_Obs._ The shells composing this well defined genus, are commonly called screws, a name to which the spiral grooves of most of the species seems to entitle them. Fig. 370, T. imbricata.

TYMPANOSTOMA. Schum. (_Timbrel mouth._) POTAMIS, Brongn.

TYPHIS. Montf. A genus composed of MUREX tubifer, Auct. and other similar species, which have the canal closed and a perforated tube between each varix on the angulated part of the whorls. Besides the fossil species originally described, there are now five species known, which are figured in part 200, of the Conchological Illustrations by the Author. Typhis tubifer, fig. 397.

ULTIMUS. Montf. (_The last._) A genus composed of OVULUM gibbosum, Auct. fig. 443, and other species in which the canals are not distinctly defined, nor elongated. This fanciful name is given to the genus on account of its being described in the last page of the book.

UMBILICATED. (_Umbilicatus._) Having an umbilicus, as Nautilus umbilicatus.

UMBILICUS. (_A navel._) The hollow formed in spiral shells when the inner side of the volutions do not join each other, so that the axis is hollow. The umbilicus is marked with the letter u in Helix algira, fig. 279. The term is also used to express any small, neat, rounded hollow.

UMBO. (_The boss of a buckler or shield._) The point of a bivalve shell above the hinge, which constitutes the apex or nucleus of each valve, from which the longitudinal rays diverge, and the lines of growth, commencing at the minutest circle, descend in gradually enlarging concentric layers to the outer margin. The umbones will be marked with the letter _u_, in Cytherea, fig. 117.

UMBRELLA. (_A little shade._) _Fam._ Semiphyllidiana, Lam. Patelloidea, Bl.--_Descr._ Patelliform, sub-orbicular, compressed, rather irregular; apex slightly raised, placed near the centre; margin acute; internal surface with a central, callous, coloured disc, surrounded by a continuous, irregular muscular impression.--_Obs._ This genus is known from Patella, by its continuous muscular impression. It is commonly called the Chinese Umbrella shell. There are but two species at present known; the U. Mediterranea, and the U. Indica, fig. 233.

UNDATED. (_Unda_, a wave.) Waved.

UNDULATED. (_Undulatus._) Minutely waved.

UNGUICULATED. (_Unguis_, a nail or hoof.) An unguiculated operculum is one in which the layers are disposed laterally, and the nucleus constitutes part of the outer edge.

UNGULINA. Daud. (_Ungula_, a nail or claw.) _Fam._ Mactracea, Lam. Conchacea, Bl.--_Descr._ Equivalve, sub-orbicular, sub-equilateral, with margins entire, simple, closed all round; hinge with one short, sub-divided cardinal tooth in each valve, and a very minute additional tooth in one valve, an oblong ligamentary pit divided into two portions, one of which receives the cartilage, the external ligament is immediately below the umbones; muscular impressions, two in each valve, oblong; impression of the mantle entire. U. transversa, fig. 88. Coast of Africa.

UNI-AURICULATED. Having one AURICLE. See AURICULATED.

UNICORNUS. Montf. MONOCEROS, Auct.

UNIO. (_A pearl._) _Fam._ Nayades, Lam. Submytilacea, Bl.--_Descr._ Inequilateral, equivalve, regular, free, pearly within, covered by a smooth epidermis without; umbones prominent, generally corroded; muscular impressions two in each valve, lateral, distant; the anterior composed of several small divisions; hinge varying in age, species, and individuals.--_Obs._ The above description is framed so as to include all the genera of the Lamarckian Nayades, together with Castalia, which are placed in the family Trigonacea, they are all fresh-water shells, commonly called fresh-water muscles. The distinctions of the various genera into which they have been divided, will be found in their respective places, and under the name Nayades. They are all represented in figures 140 to 152. Of these fig. 145 to 148, are more generally considered as forming the genus Unio.

UNIOPSIS. Sw. A sub-genus of Alasmodon. Sw. p. 382.

UNIVALVE. (_Unus_, one; _valva_, valve.) A shell consisting of a single piece, as distinguished from Bivalves and Multivalves, which are composed of two or more principal pieces. Spiral shells having an operculum, are called sub-bivalves by some authors.

UPPER-VALVE. The free valve in attached bivalves.

UVIGERINA. D'Orb. A genus of microscopic Foraminifera.

VAGINA. Megerle. SOLEN _vagina_, Auct.

VAGINULA. (_A little sheath, the husk of corn._) _Class_, Pteropoda, Lam.--_Descr._ Pyramidal, slightly inflated in the centre, thin, fragile; aperture oblong, with the edges turned slightly outwards.--_Obs._ The little shells of this genus, which are only known in a fossil state, differ from Cuvieria in being pointed at the extremity. Found in the tertiary beds of Bordeaux. V. Daudinii, fig. 225.

VAGINULINA. D'Orb. A genus of microscopic Foraminifera.

VALVATA. Müll. _Fam._ Peristomata, Lam. Cricostomata, Bl.--_Descr._ Thin, turbinated; spire short, composed of from three to six rounded whorls; aperture circular; peritreme acute, entire; operculum horny, spiral.--_Obs._ This genus of small shells resembles Cyclostoma, from which the recent species may be known by the horny texture of the external surface, being fresh-water shells. The fossils of course belong to the fresh-water formations. V. piscinalis, fig. 322. Europe and North America.

VALVES. (_Valva_, a door, a folding piece.) The two pieces composing a bivalve shell, which close upon each other, turning upon a hinge consisting of a ligament, cartilage, and teeth. See BIVALVE, MULTIVALVE, and UNIVALVE.

VALVULINA. D'Orb. A genus of microscopic Foraminifera.

VARIX. (_A swelling vein._) A varix is formed on the outer surface of a spiral shell, by the thickened, reflected edge of a former aperture, after fresh deposits of testaceous matter have increased the size by adding to the growth of the shell beyond it. In this manner there are frequently many varices, or edges of former apertures, in various parts of the spire and the body whorl. They are sometimes placed at regular distances from each other, as in Harpa, fig. 419; sometimes _continuous_, as in Ranella, fig. 394; sometimes _discontinuous_, as in Triton, fig. 398; sometimes _ramose_, as in Murex, fig. 395; sometimes _simple_, as in Scalaria, fig. 351; sometimes _spinose_, as in Murex spinosus. The term _varix_ has also been applied to any swelling ridge, such as that on the lower part of the columella of Ancillaria, fig. 456.

VELATES. Montf. NERITINA perversa, Auct. Fig. 326.

VELLETIA. Gray? A genus described as differing from ANCYLUS in being dextral. VELLETIA lacustris, ANCYLUS lacustris, Auct. fig. Sowerby Gen. fig. 2.

VELUTINA. Auct. _Fam._ Macrostomata, Lam.--_Descr._ Sub-globose, covered with a velvety epidermis; spire short, composed of two rapidly enlarged ventricose whorls; aperture large, sub-ovate; peritreme thin, entire, separated from the last whorl; columella tortuous, thin.--_Obs._ This shell does not resemble any other genus in the family. Fig. 337. Northern Seas.

VENERICARDIA. Lam. A genus composed of the shorter species of Cardita.

VENERIRUPIS. Lam. (From _Venus_ and _rupis_, a rock.) The oblong species of Venus Auct. which live in cavities of rocks and stones. This genus is united by Sowerby with some other species of Venus under the name Pullastra. V. Vulgaris, fig. 97.

VENTRAL. (_Venter_, the belly.) The margin of a bivalve shell opposite the hinge. The under valve in Brachiopodous bivalves is the ventral valve. The ventral surface of an univalve spiral shell is that which faces the observer when the aperture is placed towards him. The ventral part of the whorls of symmetrical convolute shells, is the inner part, that which is nearest to the spire.

VENTRAL SIPHON. In symmetrical convolute univalves, is one placed near the inner edge of the whorls.

VENTRICOSE. (_Ventricosus._) Swelled, rounded out, (_bombé Fr._) as Harpa ventricosa, fig. 419.

VENUS. Auct. (_Goddess of Beauty._) _Fam._ Marine Conchacea, Lam. Conchacea, Bl.--_Descr._ Equivalve, inequilateral, sub-globose, sub-ovate, transverse, externally rugose, striated, ribbed, cancellated or smooth; margins entire, simple, close; hinge with three more or less distinct cardinal teeth, diverging from the umbones in each valve; muscular impressions two, lateral, distant; palleal impressions sinuated posteriorly; ligament external.--_Obs._ This extensive genus, including some bivalves of splendour and beauty, justifying the name given to it, may be known from Cytherea by the absence of a lateral tooth, which is found near the cardinal teeth in the latter. Artemis is distinguished not only by its beautiful form, but by the deep angular sinus in the palleal impression. Fig. 119, 119 a. Found mostly in temperate and tropical climates.

VERMETUS. Adanson. _Fam._ Scalariana, Lam. Cricostomata, Bl.--_Descr._ Spiral at the apex, irregularly twisted towards the aperture; aperture round, small.--_Obs._ This shell resembles the Serpulæ in general appearance, although it is regularly spiral near the apex. The animal is known to be a true mollusc, rather nearly allied to that of the genus Dentalium, which is also placed wrongly in the Lamarckian system. Vermetus Lumbricalis, fig. 345. Coast of Africa.

VERMICULAR. (_Vermicularis._) Worm-shaped, tubular, serpentine. _Ex._ Vermilia triquetra, fig. 7.

VERMICULARIA. Lam. VERMETUS, Adanson; afterwards VERMETUS, Lam.

VERMILIA. Lam. A genus composed of species of Serpula, which are attached by the whole length of the shell, no part being free. Vermilia triquetra, fig. 7.

VERTEBRALINA. D'Orb. A genus of microscopic Foraminifera.

VERTEX. Apex.

VERTIGO. Müll. _Fam._ Colimacea, Lam.--_Descr._ Cylindrically fusiform, sinistral, hyaline; aperture marginated, sinuated, denticulated on the inner edge; peristome sub-reflected.--_Obs._ This genus of minute land shells, resembles Pupa, but is a reversed, hyaline shell. Vertigo pusilla, fig. 293. Europe.

VERRUCA. Schum. CLITIA, Leach.

VESICA. Sw. A sub-genus of Bulinus, Sw. p. 360.

VEXILLA. Sw. A genus of "Nassinæ," Sw. thus described: "General shape of _Purpura_, the inner lip flattened and depressed; the outer, when adult, thickened, inflected and toothed; aperture wide; picta _Sw._ Chem. pl. 157, f. 1504-5." Sw. Malac. p. 300.

VIRGULINA. D'Orb. A genus of microscopic Foraminifera.

VITRELLA. Sw. A sub-genus of "Bullinæ," Sw. Lardn. Cyclop. Malac. p. 360.

VITRINA. Drap. (_Vitreus_, glassy.) _Fam._ Limacinea, Lam. and Bl.--_Descr._ Ovate, thin, glassy, fragile; spire short; last whorl large; aperture wide, transverse; peritreme simple; columella spiral, linear.--_Obs._ This genus of land-shells is not known in a fossil state. The recent species are found among moss and grass, in shady situations. De Ferussac has divided this genus into Helicolimax, fig. 263, and Helixarion, fig. 262.

VITULARIA. Sw. A genus of "Muricinæ," Sw. thus described: "General habit of _Muricidea_, but the inner lip is depressed and flattened as in the _Purpurinæ_; varices simple, nearly obsolete. Tuberculata, Sw. En. M. 419. fig. 1. (_Murex vitulinus_, Auct.)" Sw. p. 297.

VIVIPARA. A generic name given by Montfort, and retained by some authors for PALUDINA, Lam. on account of the animals being _viviparous_, i. e. the young being perfectly formed before they leave the ovaries.

VIVIPAROUS. See VIVIPARA.

VOLUTA. Auct. (_Volvo_, to revolve.) _Fam._ Columellaria, Lam. Angyostomata, Bl.--_Descr._ Sub-ovate, rather angulated, thick, generally tuberculated, smooth; spire short, conical, with a mammillated apex; aperture generally angulated, large, terminating anteriorly in a deep notch; columella smooth, with several plaits, of which the lowest is the largest; outer lip thickened within.--_Obs._ The genus Voluta, as left by Linnæus, is only characterized by the folds on the columella, and includes many shells which, although they agree in this respect with the genus, are yet quite opposite to each other in all other characters. Thus the Auriculæ, which are land shells, and have the aperture entire, are mixed up with others which are marine, and have a canal, as Turbinellæ, and the Fasciolariæ, and others which have merely a notch, as the true Volutes. This genus, as it is circumscribed at present, includes a great number of beautiful shells, most of which are rich in colouring. CYMBA and MELO have been separated by Mr. Broderip from the genus VOLUTA of Lamarck, for reasons stated in their respective descriptions. Fig. 443.

VOLVARIA. Lam. (_Volva_, a shuttle.) _Fam._ Columellaria, Lam.--_Descr._ Cylindrical, convolute, spirally striated; spire very short, nearly hidden; aperture narrow, as long as the whole shell; columella with three oblique plaits; outer lip dentated.--_Obs._ The Volvaria are only known in a fossil state, and resemble some species of Bulla in general form, but are distinguished by the plaits on the columella. Fig. 439, V. concinna.

VOLUTELLA. Sw. (_A little volute._) A genus composed of those species of MARGINELLA, Auct. which have the spire concealed, and the aperture smooth within. Fig. 438, PERSICULA of Schumacher.

VOLUTILITHES. Sw. (_Voluta_, and [Greek: lithos], _lithos_, a stone.) A genus composed of some fossil species of Voluta, which have the plaits on the pillar generally numerous, indistinct, and sometimes wanting altogether, with a pointed spire. Fig. 436, V. spinosa.

VOLUTION. See WHORL.

VORTICIALIS. Lam. A genus of microscopic Foraminifera.

VULSELLA. Lam. (_A little tongue._) _Fam._ Ostracea, Lau. Margaritacea, Bl.--_Descr._ Equivalve, irregular, longitudinal, compressed, oblong; umbones separated by a slight area in both valves; hinge with a large pit in the centre, containing the cartilage, the ligament being spread over the areas; muscular impressions, one on each valve, sub-central, oblong.--_Obs._ This genus differs from Ostræa in the equality of the valves, and in having a hollow pit in the hinge for the cartilage. Vulsella lingulata, fig. 185.

WATERING-POT. Aspergillum, fig. 44, commonly so called on account of the resemblance of its perforated termination to that of the spout of a watering-pot.

WENTLE TRAP. Scalaria pretiosa, commonly so called.

WHORL. A complete turn or revolution round the imaginary axis of a spiral shell. The last whorl is called the _body-whorl_. The whorls are described as _non-contiguous_, when they do not touch each other; _continuous_, in the opposite case. _Depressed_ when they are flat. They are _angulated_, _heeled_, or coronated; _distinct_, or indistinct. They are sometimes, as in Cypræa, hidden by the last whorl.

XYLOPHAGA. Sow. ([Greek: xulon], _zylon_, wood; [Greek: phagô], _phago_, to eat.) _Fam._ Tubiscolæ, Lam.--_Descr._ Equivalve, globose, closed at the back; with a large, angular hiatus in front; hinge with a small curved tooth advancing from beneath the umbones in each valve.--_Obs._ This shell, which is found in a cylindrical cavity, eaten in wood by the animal, resembles Teredo, but has not the shelly tube, nor the posterior hiatus. X. dorsalis, fig. 50, 51.

XYLOTRYA. Leach. XYLOPHAGA, Sow.

ZONITES. Montf. A genus formed of Helix Algira, and other similar species with depressed spires and large umbilici; included in the sub-genus Helicella. Fig. 279.

ZUA. Leach. A genus described as differing from Bulinus in having a polished epidermis, and a thickened, not reflected lip. Zua lubrica, B. lubricus, Auct.

ZURAMA. Leach. A sub-genus of Helix. H. pulchella, Auct. Gray's Turton, p. 41.

* * * * *

EXPLANATION OF PLATES,

AND SYSTEMATIC VIEW OF THE

LAMARCKIAN ARRANGEMENT.

_Class_, ANNELIDES. _Order_, SEDENTARIA. _Fam._ Dorsalia.

FIG.

1. Siliquaria anguina. Agathirses, Montf.

_Fam._ Maldania.

2. Dentalium octogonum.

3. Pharetrium fragile, with the outer tube broken.

_Fam._ Serpulacea.

4. Serpula bicarinata.

5. Spirorbis Nautiloides, on sea-weed.

6. Galeolaria decumbens, on a Conia.

7. Vermilia triquetra.

8. Spiroglyphus, on a portion of Patella.

9. Magilus antiquus, old shell. Campulotus, Guild. (from Guerin.)

10. The same, in a young state.

11. Leptoconchus striatus.

12. Stylifer astericola.

13. The same, in a portion of Star-fish.

_Class_, CIRRIPEDES. _Order_, SESSILE CIRRIPEDES

14. Tubicinella Balænarum.

15. Coronula Testudinaria. Chelonobia, Leach, Astrolepas, Klein.

16. ---- Balænaris. Cetopirus, Ranz.

17. ---- diadema. Diadema, Ranz.

18. Chthalamus, Ranz. (from Blainville.)

19. Platylepas pulchra, Leach. One valve separate, showing the inside.

20. Clitia Verruca, Leach. Octhosia, Ranz. Verruca, Schum.

21. Conia porosa. Teraclita, Schum.

22. Elminius Leachii.

23. Catophragmus imbricatus, (from Sowerby's Genera.)

24. Octomeris angulosus, (from Sow. Gen.)

25. Balanus tintinnabulum.

26. ---- Montagui. Acasta, Leach.

27. ---- galeatus, Conoplæa, Say.

28. Creusia gregaria. _b._ showing the internal structure.

29. Nobia grandis.

30. Savignium crenatum. } } 31. Pyrgoma cancellata. } Pyrgoma, Auct. } 32. Adna Anglicum. } } 33. Megatrema semicostata.}

_Order_, PEDUNCULATED CIRRIPEDES.

34. Pentelasmis lævis. Antifa, Lam. a. anterior.

35. Scalpellum vulgare.

36. Smilium Peronii.

37. Pollicipes polymeus. Ramphidoma, Schum.

37*. Pollicipes mitellus. Capitulum, Klein.

38. Brismæus Rhophodius.

39. Lithotrya dorsalis. Absia, Leach, Litholepas, Bl.

40. Ibla Cuvieriana.

41. Heptalasmis Warwickii. Octolasmis, Gray.

42. Cineras vittatus.

43. Otion Cuvieri.

_Class_, CONCHIFERA. _Order_, C. DIMYARIA. _Fam._ Tubicolaria.

44. Aspergillum vaginiferum. Penicillus, Brug.

45. Clavagella, a fossil species.

46. Teredina personata.

47. Lignite, pierced by Teredinæ.

48. Teredo navalis; _a_, tube (from Sowerby's Genera.)

49. Wood bored by Teredo.

50. Xylophaga dorsalis. Xylotrya, Leach.

51. The same, in wood. (This would be more properly placed in Pholadaria.)

52. Gastrochæna Modiolina, in the tube (from Sowerby's Genera.)

53. Fistulana Clava. } } (From Sowerby's Genera.) 54. Tube of the same. }

_Fam._ Pholadaria.

55. Pholas Dactylus; _a_, plates of the hinge.

56. ---- papyracea. Pholadidæa.

57. Pholadomya Candida.

58. Galeomma Turtoni.

59. Front view of the same.

(Here Xylophaga should be placed, see Tubicolaria.)

_Fam._ Solenacea.

60. Solen ensis. Ensis, Schum. Ensatella, Sw.

61. Solen radiatus. Solenocurtus, Bl. Leguminaria, Schum. Siliqua, Megerle.

62. Lepton squamosum. (from Turton.)

63. Novaculina gangetica.

64. Glanconome Chinensis.

65. Panopæa Australis. } } (From Sowerby's Genera.) 66. Hinge of Panopæa Faujasii.}

67. Glycimeris Siliqua.

68. Solenimya Mediterranea.

_Fam._ Myaria.

69. Anatina rostrata. Auriscalpium, Megerle.

70. Anatinella Sibbaldii.

71. Mya truncata.

72. Periploma inæquivalvis. Osteodesma, Desh. _a_, bone of the hinge, (from Blainville.)

73. Myochama anomioides; lower valve with clavicle, and hinge of upper valve.

74. External view of the same, attached to a Trigonia.