134 



SCIENCE-GOSSIP. 



is darker than the other forms of P. achatina, 

 except the variety infrafasciata, being of a blackish- 

 brown above, a little paler below. It is, however, 

 larger than that variety, and does not possess the 

 white band below ; the umbilicus is also much 

 deeper, the shell being in that respect more like 

 the variety obesa, which it also resembles in the 

 sloping underside ; the aperture is proportionately 

 larger than in that variety. The spiral lines on 



there are also important differences in the arma- 

 ture, the lower horizontal parietal fold being very 

 short, not extending on either side beyond the two 

 lower arms of the main fold (see fig. 87^, which 

 shows part of the parietal wall with its folds). Of 

 the palatal armature, the first, second, and third 

 folds are more elevated ; the first is bilobed, and 

 above the posterior portion of the second occurs a 

 very short additional fold. The vertical plate is 

 also more elevated, and in place of the usual 

 denticle posteriorly to its lower extremity is 

 found an elevated ridge quite united to the 

 plate. Fig. Sja shows the anterior and fig. 

 876 the posterior aspect of both armatures. The 

 specimen figured is in the collection of Mr. 

 Ponsonby. 



{To be continued.) 



Fig. 86.— Plectopylis achatina var. casta'nea. 



the last two and a-half whorls are visible without 

 the aid of a lens. The specimen figured was 

 received by me from Miss Linter. 



Plectopylis achatina var. byeviplica (*) (figs. Sja-c) 

 has a much shallower umbilicus, and is thinner 

 and more fragile than any other form of P. achatina 

 known to me. It is somewhat like the variety 

 infrafasciata, but it is devoid of the white band on 

 the lower side ; the last whorl also widens a little 

 more than in that variety, but is less deflected, and 

 the aperture is more sloping from top to base ; 



b c 



Fig. 87. — Plectopylis achatina var. breviphca. 



(*) Plectopylis achatina var. breviphca, n. var. (figs. S'/a-c), 

 differs from the type and all the other known varieties by the 

 much more shallow umbilicus. It resembles the variety 

 infrafasciata in outline, but it is of a uniform dark brown, 

 with a somewhat polished surface, and the last whorl widens 

 more suddenly at the aperture. The basal horizontal parietal 

 fold is very short, not extending on either side beyond the 

 two lower arms of the main median fold ; the first palatal 

 horizontal fold is considerably more elevated than in the 

 other forms, and is bilobed ; the second and third horizontal 

 folds are also more elevated, the latter fold has a short fold 

 above its posterior portion ; the vertical plate is also more 

 elevated, and in place of the usual denticle posteriorly to its 

 lower extremity is .m elevated ridge, quite united to the 

 plate. — Mjijf^.r diameter, ig millimetres; minor diameter,. 

 16 millin.etrcs; altitude, 7 millimetres.— Habitat, Burma.— 

 Type in Mr. Ponsonby's collection. 



