28 LIEUT.-COL. H. H. GODWIN-AUSTEN ON [Jau. 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 vfhat 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 ex- 

 tremity 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 modifica- 

 tion 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 «) 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 Byssota 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 Oocytes in its 

 dorsal lobes. The contraction o£ 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 jR. 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 amatorice (see 

 fig. 18); thus they are of a much more complicated nature than 

 in the species under review. 



In R. hrookei the male organ consists of a large pear-shaped sac, 



