3G2 



MOLLUSCA. 



ducc the water to the hraiiL-hial cavity ph^ced upon the hack, and closed in every other jilace. The 

 rcsiiiratory organ coiisit,ts in a few small leatlets, attarlied hi a transverse line to the hottum of that 

 cavity. Tlie animal appears to have no tcntacula, hut only a narrow veil upon the head. There ai'e 

 species in which the shell ^liows no appearance of the groove, and would perh^ctly resemhle a Patella 

 were it not that its vertex is turned hackwards. [We must ol>scrve, says liang, that we have seen 

 young Patelhe. to have the character of Kiphonaria, and to pre^ei've traces of it at a niuix! advanced age: 

 it is only then provisionally that we adopt this genus, and assign it a place among the lufcrohraadnaia.l 



SiGARETUs, Adans. 



The shell is llattened, with an amph; round apei'ture, and an inconsiderahle spire, v\'hose whorls enlarge 

 very rapidly, and are vi.sihIeoii the inside. It is hidden during life in the fungous shield of the animal, 

 ^^hich projects eonsideralily heyond it, as well as the fuot, and \>, the true mantle. ^Ve ohservein front 

 of this mantle an emargination and a semi-canal, the use of which is to conduct water into the hrancliial 

 cavity, but which leave no impressions on the shell. The structure indicates a transition to the following 

 family. The tentacula are conical, with the eyes at their exterior hase : the penis of tlie male is very 

 large. 



There are species on our own coasts. [Tliis remark is erroneous, unless we consider Cuvier's Sigaretus the 

 same as Pleurobranclms. Sec some remarks on the confusion in the nomenclature of tliis g-enus by Mr. Gray, in 

 the Zool. Journ. i. p. 423,] 



Coriocdla, Blainv., is a Sigaretus witli ci linrny and alinn.st niemhranous shell, lik(' that of Aplysia. 



The Cryptostoma, Blainv. — 



lias a shell very similar to Sigaretus, supported, with the head and alidomen (which it covers), on a foot 

 four times its size, cut square hehind, and \Uiich produces in front a fleshy ol>lung part that conslitLites 

 nearly one half of its mass. The animal has a Ihit iiead, two tentneula, a broad branchial cumb on tlie 

 roof of its (hn-sal cavity, and the peuib under the right tentaculum, but I have not seen any emargination 

 in the cloak. 



THE THIRD FAMILY OF TIIF FECTINIDRANCHIATA,— 

 The IlucciNOiDES,* — 

 Have a spiral shed, tlie mouth of whirdi has, near the end of the columella, a sinus or canal, for the 

 passage of the ,siplion or tube formed by an elong;Ued fuld of the cloak. The greater or less lengtli uf 

 this canal when it exists, the greater or less width of the ajierture, and the vaiious forms of the 

 columella, atTurd characters for a division of the family into genera, which can he groujicd in various 

 ways. 



Tuf!: Coxes (Comtr;, Linn.) — ■ 



Are so named from the conical figure of their shells. The spire, 



either flat or slightly raised, forms the hase of the cone, whose 



apex is at the opposite extrerrhty : the ajierlnrc is nari'ow 



rectilinear, or nearly so, extended from one end to the other, 



v\itli()iit pi-otuherance or fold, either on the columella or tin; 



margin. Tlie animal is of a thinness ]iroporti(jn.d to the a[»cr- 



(uie thrmigh which it i^^ucs : its tcntacula and jiruhoscis are 



much chniguted, and we hnd the eyes near the apex of the 



Rtrmer, f/m the ontbiile : the op'erculnin, seated ohliijnuly on the 



hinder ]iiirt of the foot, is narrow, and too ^hoii to close the 



month of the shell. 



Tiie shells of tliis t;-e]ius are in general beautifully coloured, whence 



Fi;^. 175.— ConiJi cnicrniis. jt bfippciis that they crowd our cabinets Our seas produce only a 



very few species, [of which tlicre is a full enumeration in Luinarck's Histolre natiinitcdt's Aiiimaux snns veiicbn'.)!.] 



The Cowries {('iijira^a, Linn.) — 

 Have also a [concealed or] very short spire, and ;i narrow aperture extending from one end to the 



other ; hut the shell, which is ventricose in the midillc, and almost equally narrowed at hoth ends, forms 



•■ CEjc-jual M-illi llic Paracrjjhahip/un-adioica ^}photi':Ornn.:hidla of I L,"_'iier.i wiih (i narrow nperlurc, «-c Ho nnt intt'iid In t,iiy lliai they arc 



f M. dc BL.i 

 Coiiu3, C_iprj:'.'i 



