156 



SCIENCE-GOSSIP. 



diameter, it is more raised in the spire and the last 

 whorl is less deflected in front ; there are also diffe- 

 rences in the armature as indicated below. The 

 species was described and figured by Lieut. - 

 Colonel Godwin-Austen in the " Proceedings of 

 the Zoological Society " for 1874, p. 609, t. 

 73. f- 3i where he states that it occurred in 

 great abundance on the slopes of the peak of 

 Shiroifurar, north-east of Munipur, at an altitude 

 of 8,000 to 9, 000 feet, and only in the short 

 grass skirting the edge of the forest. The specimen 

 figured is from the Daffla Hills, and is in the 

 collection of Mr. Ponsonby. The parietal armature 

 is similar in character to that of P. perarcta, but 

 the principal horizontal plate is more flexuous, being 

 somewhat raised towards the vertical plate and again 

 towards the aperture before its final deflection at 

 its junction with the parietal callus ; it is also much 

 broader. The second horizontal plate is also 

 broader and flexuous, while both are a little more 

 distant from the vertical plate (see fig. 20a). The 

 vertical plate is smaller than in the species just 

 mentioned, and rounded at the top, while it is not 

 deflected posteriorly below as in that species. 

 There are, besides, two small very short ridges 

 given off from the extremities of the vertical plate 

 on its posterior side ; the third horizontal fold is 

 also a little longer as well as more flexuous than 

 in P.perarcta. The chief difference, however, is in 

 the palatal plates, as may be seen on reference to 

 figs, -zoh-d. The first is horizontal, small and 

 bilobed, close to the suture, then come two hori- 

 zontal plates, small but comparatively broad, next 

 a broad and strong vertical bilobed lamella, giving 

 off on the posterior side two short ridges from the 



iryrrr^ 



Fig. 21. — Plectopylis de.xtrorsa. 



base of the lobes (see fig. 2od), and below this a 

 small but broad horizontal plate with a small 

 tooth a little above and posterior to it. Fig. 20& 

 shows the barriers from the side of the aperture, 

 and fig. 2.0c from behind. 



Plectopylis dextrorsa (figs. 2ia-c) was originally 

 described by Mr. Benson in " Annals and Maga- 

 zine of Natural, History " (3), v. (i860), p. 246, as a 

 daxtral form of P. hiophis, from Tenasserim, and it 



was figured in Hanley and Theobald's " Concho- 

 logia Indica," t. 13, f. 9, and in Tryon's "Manual 

 of Conchology " (2), iii., t. 35, f. 2, as P. refuga, var. 

 dextrorsa. Lieut-Colonel Godwin-Austen was the 

 first to point out its specific distinctness from 

 P. hiophis (Proc. Zool. Soc, 1875, p. 44), and he 

 raised it to specific rank under the name of 

 Plectopylis dextrorsa. He further stated that it is 

 very close to P. pseudophis, but his figure of that 

 species (loc. cit., 1874, t. 74, f. 3) does not bear out 

 this view, and, after a careful comparison, I am 

 inclined to consider its nearest ally to be 

 P. br achy discus. The shell, however, is smaller 

 than that of the last-named species, measuring 

 16 millimetres in diameter, and there are 

 differences of importance in the armature. The 

 parietal vertical plate is rounded at the top, 

 and forms a short ridge posteriorly, while 

 another but much smaller ridge is formed at 

 the base, first proceeding a little horizontally and 

 then deflecting a little towards the suture (see 

 fig. 2i«) ; the principal horizontal plate begins at 

 a little distance from the vertical plate as in 

 P. br achy discus, but it is placed above the middle 

 and therefore nearer the suture than in that species, 

 and instead of revolving parallel with the suture it 

 bends upwards a little and proceeds without 

 interruption as far as its junction with the raised 

 ridge of the parietal callus (see fig. 21a) at the 

 aperture, while in P. brachydiscus it is inter- 

 rupted. Other differences in the palatal armature 

 will be observed on reference to fig. 216, where the 

 inner side of the shell wall bearing the folds and 

 teeth is shown. The first plate is long and hori- 

 zontal ; the second is also horizontal, and bifurcates 

 as in the other species ; next come two series of 

 three folds each, the anterior ones horizontal, the 

 posterior ones smaller and obliquely descending ; 

 and lastly we have a strong broad tooth parallel 

 with and near to the suture, with a smaller one 

 posteriorly in a line with it. Fig. 21c shows the 

 barriers of this species — parietal and palatal — from 

 the posterior side. 



P.S. — With the Editor's permission I take this 

 opportunity of mentioning, that as yet I have been 

 unable to obtain specimens of the following species 

 of the genus under consideration : Plectopylis 

 diptychia, P. muraia, P. oglei, P. tmmipurensis, P. 

 feddeni, P. biforis, P. jugatoria, P. revoluta, P. 

 phlyaria, P. vallata, P. eugeni, P. lambacensis ; and 

 that I should much like to be favoured with them, 

 either on loan or otherwise. In the case of mala- 

 cologists having duplicate specimens, I should 

 hope to be able to make a suitable exchange, as 

 for instance. Gorilla fryae, the new species described 

 in the September number of this magazine. — 

 Address : 5, Giesbach Road, Upper Holloway, 

 London, N. 



(To be continued.) 



