TROCHID.fi. 



1108 



Shell of Solarium tir'ujatum 

 a 



a, the animal and nhcll of Solarium rariryalum, together with the operruluro, 

 feen from below ; ft, the operculum. (Astrolabe.) 



Trockia. Animal well known, and as characterised above. Shell 

 thick, ordinarily nacreous, troclioid, with the spire sometimes lowered 

 (iturbaissee), and at others rather lofty (eUucee) and pointed at the 

 miuimit ; trenchant or oarinated on its circumference, umbilicated or 

 not ; aperture depressed, angular or subangular, with disunited 

 borders, the right lip trenchant; the colutnella bent, twisted, and 

 often projecting in front. 



Operculum horny, delicate, consisting of numerous narrow spiral 

 whorls, increasing slightly from the centre to the circumference, 

 (Blainv.) 



The number of recent species of Trochnt given by Woodward is 

 150, and fossil forms 360. The fossil forms are found in the Devonian 

 rock*. 



Thaw plant eating marine gastropods are very widely diffused, there 

 being few seas without some of the species : they have been captured 

 at depths varying from the surface to 45 fathoms, creeping on rocks 

 and sea-weeds, sand, sandy mud, and gravel. 



T. obductu. Shell conico-pyramidal, nodulous and granulous, 

 coloured with green and white ; the whorls tuberculato-nodo.se, and 

 girt with many granose circles ; the lost whorl, as it were, removed or 

 taken away (dempto) ; the lower surface planulate ; the lip siuuatt J 

 at the base. 



Troctau obtliuut. 



, anterior part of the animal, a portion of the oprrculum being rUible at the 

 lower part of the flriirr ; fc, operculum. 



with black. The muzzle is very wide, with a black riband near it* 

 border, as well as the head, which is moreover dotted with greenish. 

 The foot is yellow below, and so dotted with brown on its sides that 

 it appears black. The edge of the mantle is variegated with brown 

 and greenish. The fringes of the feet are white and without filament*. 

 (Quoy and Oaiui.) 



Lamarck gives the Indian Ocean a the habitat of his species. 

 Messrs. Quoy and Oaimard, who captured the individual above 

 described at Tonga, remark that in colour it is T. oMucia, but th.>t it 

 tends to T. acutui in its suddenly-pointed spire. 



The same zoologists observe that the opcrcula of Trochi known in 

 collections are nearly all of a chestnut-colour. This, they remark, is 

 ordinarily due to the action of the air, for on the living animal they 

 are transparent and yellowish. In the very turriculated species the 

 animal draws itself back into the shell obliquely, dragging in with it 

 in this manner its operculum, which otherwise could not lie flat in the 

 aperture, which is always more or less flattened. These animals, they 

 add, show themselves but little, and hide themselves far in, so that 

 none of their parts can be perceived. It is even necessary to break 

 the first whorl of the shell in order to draw them satisfactorily. 

 (' Astrolabe,') 



'J'. imptritUa, (Genus Imperator, Montf.) Shell orbiculate-conoid ; 

 the apex obtuse, violet-brown above, white below, with transverse 

 imbricato-squamous furrows ; the whorl* turgidly convex, squamoso- 

 radiate at the margin ; the scales complicated ; umbilicus iufundibu- 

 liform. (Lam.) 



Animal- Foot oval, rather large ; the muzzle elongated in form of 

 a proboscis ; the tentacles short, white, with a black or reddish line 

 running lengthwise; ocular peduncles very stout, obtuse, the palmettos 

 hardly visible. All these parts are whitish ; the head and the mouth 

 are striated across with black and violet : this last colour belongs only 

 to the left side. The foot has some very bright marks on its sides ; 

 its lateral fringes are without filaments. 



Operculum oval, smooth, whitish, and a little convex (rondo ) towards 

 one of its extremities. (' Astrolabe.') 



Messrs. Quoy and Gaimnrd, who observe that the operculum of this 

 species determined them to place it in the genus Turbo, state that it 

 has only been hitherto found at New Zealand, where it is rare. They 

 never obtained more than one living specimen. That from which the 

 description and figure were taken was small, being only two inches in 

 diameter, comprising the spines. It was covered with calcareous 

 incrustations and marine plants, indicating the sloth of the animal. 

 They found it in the Passe des-Francai, Tasman Bay. 



TVorliu iin/Mriatii, with unluial. 



n, anterior part of animal wen from above; //, inside of opcrculura; r, out- 

 aMe of the name. 



i Anin JV, with "to" 1 nml *hort fenticK which are white with a Dr. J. K Gray mnkes the Trochidv the rocond family of his 

 brown border; the ocular peduncle* large, pointed, nnd doubly circled PodopMhalma, tho first section of the order Phylophaga in hi* 



