I02 



SCIENCE-GOSSIP. 



ARMATURE OF HELICOID LANDSHELLS. 



By G. K. Gude, F.Z.S. 

 (Continued from page 71.) 



pLECTOPYLlS polyptychia (tigs, s^a-d), from 

 -* Mount Licos, Cebu, I'hilippine Islands, was 

 described by Dr. von Mollendorff in the " Jahrbuch 

 der Deutschen Malakozoologisciien Gesellschaft," 

 xiv. (1887), p. 272. Tiie shell was figured in the 

 same volume (t. 8, f. 8) ; the armature, however, 

 was not figured, and I have pleasure in illustrating 



c d 



Fig- iS.—Plectopylis polyptychia. 



it The shell is dextral, discoid, openly umbilicated, 

 finely and regularly ribbed above, finely striated 

 below, and horny-brown in colour. The spire is 

 scarcely raised and the suture is well impressed 

 There are five and a-half to si.x convex whorls, 



September, 1897.— No. 40, Vol. IV. 



which increase slowly and regularly, the last being 

 angulated above the periphery _and scarcely descend- 

 ing in front. The aperture is diagonal, oblique and 

 heart-shaped ; the peristome is but little thickened 

 and reflexed, its margins are united by a raised 

 bilobed ridge at the parietal callus. The parietal 

 armature consists of two parallel, horizontal folds 

 revolving over one-third of the body-whorl, the 

 upper strong, and united to the raised ridge at 

 the aperture, which it bisects ; the lower thinner, 

 not reaching quite so far at the aperture (see 

 fig- 55^')- The palatal armature consists of ten to 

 twelve denticles, arranged vertically in a row, eight 

 of which are larger than the rest, elongated hori- 

 zontally, and have one or two minute ones both 

 above and below them (see fig. 551?, which shows 

 the inside of the outer wall with its denticles). 

 The shell figured is in Mr. I^onsonby's collection, 

 and measures — major diameter, 4 millimetres ; 

 minor diameter, 325 millimetres; altitude, 1-25 

 millimetres. 



Plcctopylis schistoptychia (figs. 56a-c), from the 

 Chinese province Hoo-Nan, was described and 

 figured by Dr. von Mollendorff in the " Jahrbuch 

 der Deutschen Malakozoologischen Gesellschaft, 

 xiii. (1886), p. 185, t. 6, f. 2. As in the case of 



