RECENTLY DESCRIBED SPECIES OF PLECTOPYLIS. 



47 



Plectop)'lis affinis from the Khasia Hills, has hitherto been 

 confused with Pledopylis plectostoma, but it differs in being larger 

 and much paler in colour, in having four instead of five rows of 

 hairs, which are not placed on raised ridges as in that species ; 

 the cuticle is much thinner and not plaited, while the spiral 

 sculpture is less coarse above and scarcely perceptible below, 

 where the shell is also more shining than in P. plectostoma. The 

 shell is translucent and the armature is distinctly visible through 

 its wall, while the aperture is more narrowed laterally and the 

 upper margin of the peristome is less arcuate, being a little 

 inflected. The umbilicus is also wider and scarcely angulated, 

 while the base is much more flattened. The ridge of the 

 parietal callus is more raised and more curved. The parietal 

 armature consists of a vertical plate with a very short support 

 anteriorly at the upper and lower extremities, but without the 



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Figure 3. — Pledopylis affinis, Gude. 



horizontal fold above as in P. plectostoma. The two denticles on 

 the posterior side are larger and more elongated, and below the 

 vertical plate are two short, thin, horizontal folds in a line with 

 each other (see fig. 3^, which shows the parietal wall by itself; 

 and fig. 3 c, which shows both armatures from the posterior 

 side). The palatal armature is similar to that of P. plectostoma, 

 but the posterior portions of the third, fourth and fifth folds, 

 instead of being straight and almost vertical are crescent-shaped 

 and oblique (see fig. 3^, which shows the palatal folds as they 

 appear through the shell-wall) ; an additional semi-circular fold, 

 posterior to, but a little, above the fifth fold, occurs in this 

 specimen; this, however, I have not observed in any of the 

 ether specimens. Fig. 3^ shows the entire shell enlarged. My 

 specimens were obtained from Mr. Fulton some j-ears ago ; the 

 twenty-five further specimens from the same locality, sent to me 

 for inspection by him, range from g to 1 1 milUmetres in diameter. 



