GUDE : SPECIES OF PLECTOPYLIS. 1 1 



forms which appear to be undescribed, and, although closely allied to 

 each other and to Pledobylis poiisonbyi (" Science Gossip" N.S., vol. 

 iii, page 178), they present sufficient differences to warrant their being 

 regarded as distinct. Three of the specimens in question belong to 

 the form which I now publish as a new species under the name of 

 Plectopylis mag7ia. A shell in the collection of Mr. E. R. Sykes, 

 which had been labelled P. achatina, I also refer to this species. 

 This new form differs from P. ponsonbyi in being much larger, more 

 solid, and darker in colour, in having one whorl more, in the last 

 whorl descending less abruptly, and in the whorls being more rounded. 

 There are also differences in the armature, /. e. the two parietal ver- 

 tical plates are convergent above, and the posterior one is considerably 

 longer than the anterior one (see fig. 71?), while in Plectopylis ponsonbyi 

 they are almost equal and parallel ; the anterior plate gives off ante- 

 riorly, below a short, stout ridge, not a distinct fold as in P. ponsonbyi, 

 and the thin fold near the suture is distinctly continued to the ridge 

 at the aperture, without becoming attenuated ; the two upper palatal 

 horizontal folds are much thinner, the third is short and crescent- 

 shaped, and the vertical fold is not bilobed, while there are several 

 more denticles posteriorly (see fig. if, which shows the inside of the 

 outer wall). The specimen figured, received from Miss Linter, as 

 above mentioned, is in my collection, and measures 25 millimetres in 

 diameter. A second specimen measures 22"5 millimetres in diameter. 

 The third specimen is not quite mature, the ridge on the parietal 

 callus at the aperture not being formed, but the armature is quite 

 identical with that of the mature shells. Figs. 7 a, b, r, and e are 

 natural size, figs. 7 ^and/are magnified. — (Ibid., p. 70.) 



Plectopylis lissoehlamys, CTude. 



Shell sinistral, solid, discoid, widely and deeply umbilicated, 

 polished, corneous, finely and regularly ribbed, decussated with 

 minute spiral sculpture above. Suture impressed, apex a little raised, 

 spire depressed. Whorls 7, rounded, increasing slowly, the last twice 

 as wide as the penultimate, widening towards the aperture, but not 

 constricted behind the peristome. Aperture rounded, elliptical ; 

 peristome white, rather thin, reflexed ; margins a little converging. 

 Parietal callus with a raised flexuous ridge separated from both 

 margins of the peristome by a little notch. Umbilicus wide and 

 deep. Parietal wall with a short, entering, flexuous horizontal fold, 

 which runs close up to the ridge at the aperture, and at one third 

 of the circumference from the mouth there are two rather thin 



