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Show 338 MOLLUSCA. According to the observations of Van Hassett, we should place here the SoARAB..IEUs, Montf. Which has an oval shell, the aperture narrowed by projecting and stout dentations on the side next to the columella, as well as towards the external margin; this margin is enlarged, and as the animal renews it after each semi-whorl, the shell projects most on two opposite lines, and has a c~rnpressed ~ppearance. . They feed on aquatic plants m the Archipelago of Ind1a(l). The two following genera were among the Volutre. AuRICULA, Lam. Differing from all the preceding aquatic Pulmonea in the columella, which is marked with wide and oblique flutes. Their shell is oval or oblong, the aperture elevated as in Bulimus, and the margin tumid. Several are large; we are not certain whether they inhabit marshes like the Lymnrei, or their borders like the Succinere. .fiuricula myosotis, Drap. III, 16, 17; Carychium myosoti•, Feruss. The only species in France; the animal has but two ten· tacula and the eyes are at their base; from the shores of the Mediterranean( 2 ). CoNovuLus, Lam.-MELAMPEs, Montf. Projecting folds in the columella, as in the Auricula::, but the ma~· gin of the' aperture is not tumid, and the internal lip is fine!y strl· ated; the general form of the shell is that of a cone, of wh1ch the spire forms the base. They inhabit the rivers of the Antilles(3). ( 1) Helix scarabtrus, L. , (2) Add, Voluta auris Midre, L., Martini, II, x1iii, 436-38; Chemn., ~~ c~ 1395, 1396;-Voluta auris Jurk, L., Martini, It, xliv, 449-51;-Vol. aumSiltm, Born., IX, 3-4;-Vol. glabra, Mart., II, xliii, 447, 448;-Vol. co.ffea, Chemn., IX, cxxi, 1044. (3) Volutaminuta, L., Mart., II, xliii, f. 445, or Bulimua coniformu, llrug.;Bul. mcmile, Brug., Mart., lb., f. 444;-Bul. ovulus, Br., Mart., lb., 446. GASTEROPODA NUDIBRANCHIATA. 339 ORDER II. NUDIBRANCHIAT A( 1 ). The Nudibranchiata have no shell whatever; neither are they furnished with a pulmonary cavity, their branchire being exposed on some part of the back. They are all hermaphroditical and marine animals, frequently swimming in a reversed position, with the foot on the surface, concave like a batteaux, and employing the margin of their mantle and their tentacula as oars. In the · DoRis, Cuv.(2) The anus opens on the posterior part of the back, the branch ire being arranged in a circle round it, under the form of little arbusculre, the whole resembling a sort of flower. The mouth is a small proboscis, situated under the anterior margin of the mantle, and furnished with two little conical tentacula. Two otht:l' claviform tentacula arise from the anterior superior part of the mantle. The openings of the genital organs are approximated under its right margin. The stomach is membranous. A gland interlaced with the liver excretes a peculiar fluid through a hole near the anus. The species are numerous, and some of them large. They are found in every sea, where their ova, resembling gelatinous bands, are diffused over stones, sea-weed, &c.(3) The (1) My four first orders are united by M. de Blainville in what he terms a subclw, designating them by the name of P ARACEl'HALOPllon.&. MoNoxc.a.. He makes twa orders of my Nudibranchiata; in the first, or the CYCLOBRANCHJA.TA, he places Doris and other analogous genera: in the second, or the PoLYBRANCJU.&.TA, are Tritonia and the following genera, which he divides in two families, according to the presence of two or four tentacula. (2) A n:~.me first applied by Linnrerts to an animal of this genus, which, however, he characterized badly. It was afterwards extended by Muller :md Gmelin to almost the whole of the Nudibranchiata, and restored by me to its original sig· nificatiou. (3) Species with an oval mantle projecting beyond the foot: Daris verrttcosa, L., Cuv., Ann. du Mus., IV, lxxiii, 4, 5;-Dwis argo, L., Bqhatsch, Anim. Mar., V, 4, 5;-Doris obvelata, Mull., Zool. Dan., XLVIII, 1, 2;-Dwis fusca, Id., lb., LXVII, 6, 9;-Doris ate/lata, Bomme, Act. 1-'less., I, iii, 4;-Doris pilosa, Miill., loc, cit. LXXXV, 5-8;-D. l<mlis, Id., lb., XLVII, 3-5;-D. muricata, Id., LXXXV, 2-4;-D. tuberculata, Cuv., Ann. du Mus., IV, lxxiv, 5;--D. lim/Jata, |