84 HELICID.B. 



Diam. major 10'5, minor 9*75 mm. ; alt. 7 mm. 



Hob. Assam : Khasi Hills. 



Fig. 33 d shows the outline of the spire enlarged. 



a b c d 



Fig. 33. Plectopylis plectostoma, var. exserta. 



83. Plectopylis affinis, Oude. 



Plectopylis affinis, Gude, Science Gossip, N. s. iii, 1897, p. 276, 



fig. 41 (shell and armature). 

 Plectopylis (Endothyra) affinis, Gude, op. cit. vi, 1899, p. 148. 



Original description : " Shell sinistral, somewhat widely um- 

 bilicated, disk-shaped, pale yellowish corneous, translucent, 

 radiately plicate, decussated by spiral lines above, smoother and 

 shining below. Whorls 7, narrow, increasing slowly, the last 

 widening towards the aperture, and descending a little in front, 

 rounded above, flattened below ; four lines of soft pilose hairs 

 pass round the whole length of the body-whorl, the first on the 

 angulated periphery, the second a little below it, the third midway 

 between the second and fourth, which is near the umbilicus. 

 Aperture ear-shaped, elongated vertically ; peristome white, 

 thickened and reflexed, upper margin a little depressed ; the 

 raised flexuous ridge on the parietal callus is separated from the 

 margins by a slight notch. Umbilicus deep and moderately wide. 

 The parietal armature consists of a vertical plate with two short 

 supports anteriorly, one above and one below, and two elongated 

 denticles posteriorly, one above and one below ; two free, short, 

 horizontal folds in a line occur below the vertical plate. The 

 palatal armature is composed of six folds, the first and sixth short, 

 thin and horizontal, the others longer and broader ; the second a 

 little indented in the middle, with the posterior termination raised 

 obliquely ; the third is notched in the middle, and deflects 

 obliquely posteriorly ; the fourth and fifth are in two series 

 separated by a short space, the anterior portion straight and 

 horizontal, the posterior portion crescent-shaped and obliquely 

 descending." (Gude.) 



Diam. major 10, min. 9 mm. ; alt. 5'5 mm. 



Nab. Assam : Khasi Hills. 



Plectopylis affinis had previously been confused with P. plecto- 

 stoma. 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 



