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Show 612 MAJOR GODWIN-AUSTEN ON [Nov. 17, animal could at once exude, would have the best chance of surviving. Among the species of Plectopylis at the British Museum is one labelled H.prodigium, Bs. (Mus. Cuming); this is undoubtedly II. plectostoma, Bs., the former being very likely its first M S . name. Plectopylis refuga, Gd., var. dextrorsa, I have not been able to examine ; but it probably will prove distinct. P. pettos, described (as Gorilla) by Dr. Ed. v. Martens, Malako-zoologische Blatter, 1868, p. 158, together with other shells from the Himalayas, it is difficult to place in its true position in the genus, owing to the internal structure having been left unnoticed. It would appear to be very close in form of aperture to P. serica. I know of no similar form from the Himalaya that would agree with the description. H. pulvinaris, Gould, from Hongkong, to which it is said to approach, is not known to me. I have been able to examine, by the kindness of Dr. Giinther, all the species of the genus in the British Museum, among them P. refuga, Gld. This is sinistrose. Whorls 6, with one long horizontal parietal lamella, continuous to the apertural ridge, with two free horizontal lamellae below it, the lowest being the longest, and situated close to the simple vertical barrier; below this is another moderately long horizontal free lamina. The palatal plicae are 6, the four upper lengthened ; the fifth is subvertical, and the sixth small. P. refuga is very close to P. leiophis; but in that species the long upper horizontal lamella is united to the second and shorter one below. Characters of the Genus Plectopylis. [All these forms have a lower parietal free lamella, with the exception of those marked t.] Group A. Parietal vertical lamina simple. a. Horizontal parietal lamina none. a. Palatal plicae simple. 1. sericat, G.-A. D. N.E. frontier, Naga- Hills. 2. pinacis, Bs. S. E. Himalaya. 3. munipurensis, G.-A. D. N.E. frontier, Bengal. 4. laomontana\, Pfr. D. Cambodia, Lao Mt. laomontana, small var. Cambodia. pettos, v. Martens? Himalaya? j3. Palatal plicae double, in two rows. 5. macromphalus, W . Blf. S. Darjeeling and N.E. frontier, Bengal. Khasi. 6. plectostomaf, Bs. S., epiderm hirsute. Darjeeling and N.E. frontier, Bengal. Khasi. * United by low ridge. 7. andersoni\, W . Blf. D. N. Burmah. ** Posterior row strong, oblique. 8. clathratuM'. J). Kandy, Ceylon. *** Posterior row strong, vertical. 9. retiferaf. D. Southern India. b. Horizontal parietal lamina present. * Single. 10. nagaensis, G.-A. S. N.E. frontier, Naga. |