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Show 28 LIEUT.-COL. H. H. GODWIN-AUSTEN ON [Jail. 6, kindness of Mr. Edgar Smith, I am enabled to figure (Plate VI. figs. 9, 9 a), consists of two whorls, is globose, very thin and delicate, transparent, of a ruddy brown colour, with an elongate quadrate aperture flatly convex above, and measures, maj. diam. 18*0, alt. axis 105 millim. It would be interesting to know at what age it reaches this size and its full maturity. Description of the animal from a spirit-specimen:-Foot below not divided as in Macrochlamys, &c. ; no mucous gland ; the extremity of the foot is flattened, rounded (Plate VI. fig. 4 ) ; the pallial margin very narrow and with no pallial groove (fig. 5) as seen in the genus Ariophanta, &c. In life I should say the animal was very similar to that of H. ochthoplax, Bs. There is not the slightest trace in the spirit-specimen of a mucous gland either above or below, and although von Martens in his work, * Die Preuss. Exped. Ost-Asien, Landschneck.,' says at p. 188 that in some large coarse species, as Rhysota ovum and Xesta distincta, he found the foot coarsely wrinkled, flat, and with a blunt end, the slime-gland little marked, so that on the whole it resembles the foot of Helix pomatia, yet I feel sure there would remain some indication of the gland in the spirit-specimen ; surely the divided sole of the foot would remain visible, and some modification of the pallial margin would show where the slit of the gland was situated, but in this large Bornean species there is no trace left to show that it ever existed. The dorsal lobes of the mantle (Plate VI. figs. 1, 2, 3, 3 a) are small for the size of the animal. The left dorsal lobe (we are speaking of a sinistral species) is of the ordinary form ; the right is divided into two separate parts, one anterior, the other posterior. Exactly between these two is a right or peristomial shell-lobe (see figs. 2, 3), and near the respiratory orifice at the inner and upper margin of the aperture a tongue-like left shell-lobe is given off from the margin of the left dorsal lobe. This, although much contracted by the spirit, is evidently of considerable extension when alive. (In Semper's description of Ryssota both shell-lobes are said to be absent.) So that here we have in this sinistral species an approach to Macrochlamys in its shell-lobes, and to the genus Oxytes in its dorsal lobes. The contraction of the animal shows the apertures coinciding with the male organ and the spermatheca very plainly (see Plate VI. fig. 5). The generative organs (fig. 6, nat. size) are exactly similar to those of Ryssota ovum figured by Semper in ' Reisen im Archipel der Philippinen,' pi. iv. fig. 1, and correspond also with those given on the same plate of R. porphyria, R. semiglobosa, R. dvitija, and R. bulla, simple, and having no amatorial organ. Now, in the five figures given by him of the generative organs of so-called Ariophanta on pi. iii., they all possess the amatorial organ with mucous glands and well-developed sagittce amatoriee (see fig. 18); thus they are of a much more complicated nature than in the species under review. In R. brookei the male organ consists of a large pear-shaped sac, |