1105 



TRITON". 



TROGEIDM. 



1108 



valvea are lanceolate or linear-oblong. This division includes the 

 wheat-grasses, some of which are only known as troublesome weeds. 

 The most remarkable instance of this is T. repens, Creeping Wheat- 

 Grass, Couch-Grass, or Spear-Grass. The difficulty of getting rid of 

 its creeping underground stem, the smallest portion of which if left in 

 the ground sends up a fresh bud, is the cause of this plant being so 

 great a pest to the farmer. The T. maritimum, a native of sea-coasts, 

 seems to be only a variety of this plant. 



T. junceum, Sea Rushy Wheat-Grass, T. caninmn, Bearded Wheat- 

 Grass, and T. cristatum, Crested Wheat-Grass, are other species of the 

 Agropyra. [WHEAT, in AHTS AND So. Div.] 



(Metzger, Die Getreide-arten und Wiesengraser in Botanischer und 

 Okonomischer UimiM, 1841 ; Koch, Flora Germanica ; Cyclopedia of 

 Plantt; Sinclair, Hortvt Woburnenris ; Pouchet, TraiU de Botaniyue ; 

 Babington, Manual.) 



TRITON. [AMPHIBIA; SIPHONOSTOMATA.] 



TRITO'NIA. [NUDIBBAXCHIATA.] 



TRITONOI'DEA (Swainson), a genus of Sfollusca. 



TRIURIDACE^E, Tailwortt, a small natural order of Plants belong- 

 ing to Lindley's class Dictyogens. They have the dictyogeuous 

 structure, unisexual flowers, a free perianth, and numerous 1-seeded 

 carpels. There are only two genera, Trim-it and Pdtophyllum. The 

 species of these plants were discovered by Mr. Miers and Mr. Gardner 

 in the woods of Brazil, where they delight in moist shady places. 

 Their relations are with Smilacete, Menitpermacecc, and Trilliaceif. 

 (Lindley, Veyetable Kingdom.) 



TRI'VIA. [CVPB.F.ID*.] 



TRIXA'GO, a genus of Plants belonging to the natural order 

 Serophulariacetr. It has a tubular 4-cleft calyx, a tubular 2-lipped 

 corolla, pointed capsules, and many-seeded cells. The seeds are slightly 

 angular and very minutely crenate ribbed. T. vitcosa, the only British 

 species, has a round high simple stem, a fibrous root, and opposite 

 leaves ; the upper leaves are alternate, ovate, lanceolate, sessile, and 

 acutely serrate. The flowers axillary, distant, and yellow ; the anthers 

 hairy. It is found in damp places in the west of Scotland and south 

 of Ireland. (Babington, Manual.) 



TROCHATELLA (Swainson), a sub-genus of Motlusca belonging to 

 the family Hdicina. [HELICID.B.] 



TROCHELLA (Swainson), a sub-genus of Calyptnea, Lam., placed 

 by him under the family Haliolidrr. The shell is conical, patelliforui ; 

 spire central, of two or more whorls ; umbilicus closed. 



T. auricttlata Sow. (' Man.,' f. 236) ; and T. pikui (' Man.,' ff. 237-8), 

 may be given as examples. 



Professor Owen has contributed a most interesting addition to our 

 knowledge of tbia genus, in his paper read before the Zoological 

 Society of London, on the 8th November, 1842, on the anatomy of 

 Lilhedaphia longirostrii, the synonyms of which he gives as " Calyptrcea 

 ll'iitiyi, Dufo (?) upper valve, Calyptrcea equcttrii, auct. (?) Mitrulana 

 ffjtiextris, Schumacher." 



TRO'CHID^E, a family of Turbinated Gasteropcdous Mollttsca. 

 The genus Trockui of Linnaeus was placed by him between Murex 

 and Tui-bo, in his last edition of the Systema Natune,' and comprised 

 2'! species. 



The Trochoidea of Cuvier form the first family of his Pectini- 

 branchiate Gastropods [PECTINIBIIANCHIATA], and are defined by him 

 KB distinguishable by their shell, whose aperture is entire, without 

 notch or canal for a mantle-siphon, the animals being destitute of one ; 

 and by an operculum or some organ in lieu of it. They are, Cuvier 

 observes, the Paracephalophora Dioica Asiphonobranchiata, of M. De 

 Blainville. 



M. De Blainville makes the Gonioitomata his first family of the 

 order Atiphonobranchiuta, and includes within it the great genus 

 Trochut, Linn., only. He describes the animal as spiral, having the 

 sides of the body often ornamented with digitated or lobated appen- 

 dages, and provided with a short foot rounded at its two extremities ; 

 the head furnished with two tentacles, more or less elongated, carrying 

 the eyes on a convexity of their external base, which is often suf- 

 ficiently distinct to render the eye subpedunculate ; mouth without 

 any upper tooth, with a lingual spiral riband ; anus on the right, in 

 the branchial cavity, which holds one or two unequal comb-like 

 bronchia; ; organs of generation terminating in a female individual on 

 the right in the branchial cavity, and in a male individual in a sort of 

 triangular tonguelet sustained by a small ossicle. Shell subplanorbic 

 or trochiform ; the spire elevated, sometimes depressed (surbaissee), 

 and more or less carinated on its last whorl, which forms a flat circular 

 base ; a moderate, depressed, and often nearly quadrangular aperture, 

 with its external or right lip trenchant, angular, or folded iu the 

 middle. Operculum horny, circular, with a submediau summit, rolled 

 regularly into a spiral ; the whorls of the spire narrow and numerous. 



M. De Blainville observes that all the species of this family are 

 phytiphagous, marine, and live upon the rocks on the shore of the sea. 

 He divides the group into Solarium and Trochus. 



fvilarium. Animal unknown. Shell orbicular, rolled up (enroulcSe) 

 nearly on the game plane, or planorbic; spire very much lowered 

 (surbaiiwe'e) ; a large conic umbilicus, with its edges denticulated or 

 not at the entrance ; aperture not modified by the last whorl of the 

 spire, which is entirely flat; no columella. Operculum unknown 

 (Blainville). 



HAT. HIST. BIT. TOt. IV. 



The number of recent species recorded by Woodward is 25, and of 

 fossil 56. 



The species of this genus hitherto found have occurred in the seas 

 of the warmer climates. The Mediterranean, the Indian Ocean, the 

 coasts of Tranquebar, the South Seas, and those of Australia are the 

 localities recorded by Lamarck. The specimens have b?en found 

 near the shore it seems to be a littoral genus on rocks and weeds. 



S. persfectivum. Shell orbiculate-conoid, longitudinally-striated, 

 whitish-yellow, with articulated belts of white and brown or chestnut 

 near the sutures; the notches of the umbilicus small. (Lamarck.) 

 Animal with a large foot widened in front, and having a very strongly 

 developed marginal furrow, yellowish on the sides, marked with a 

 black stria above. The head presenting a large escutcheon. The 

 tentacles short, stout, and marked with two longitudinal black bands 

 on the sides. At their base are placed the eyes on very short 

 pedicles. The branchial cavity appeared to be partially divided in 

 two, lengthwise, by a sort of fold. The intestine describes two rather 

 considerable circumvolutions before it passes the liver. Operculum 

 large, oval, membranous, and strongly but sparingly spiral at one of 

 its extremities. The colour is yellowish, like that of the whole animal. 



Messrs. Quoy and Gaimard, who have given this description of the 

 animal in the ' Zoologie ' of the Astrolabe, state that they know 

 nothing of the habits of this species, which was brought to them 

 nearly dead by a Malay of Aiuboyna. 



Solarium pcrspectivum. 



a, front view ; 4, seen from below ; c, operculum ; d, anterior part of the 

 animal. (Operoulum and animal from the ' Atlas ' of the Astrolabe.) 



I?, variegatum. Shell orbiculate-convex, transversely sulcated, longi- 

 tudinally striated articulately, variegated with white and bay ; umbili- 

 cus patulous and crenelated. (Lamarck.) Animal nearly of the same 

 colour as the shell, which it secretes; for it is brown, dotted with 

 black, on all parts. The tentacles are stout, long, obtuse, carrying 

 the eyes at a certain distance from their base on a convexity. The 

 foot is oval, rather largo, widened, notched, and auriculated in front. 



It carries at its posterior part one of the most singular of opercula, 

 of an unique form among molluscs, and already known iu collections 

 by the account of M. de Roissy, but without the knowledge of the 

 species to which it was to be referred. It is a long, solid, calcareo- 

 membranous cone, carrying membranous lamella; spirally throughrout 

 its length. The interspaces are as it were ribanded. (Quoy and 

 Qaimard.) It is found at Carterct Harbour iu New Ireland. 



4 B 



