84 HELICID.«. 



Diaiu. major 10*5, minoi' 9'75min. ; alt. 7 mm. 



Hah. Assiiin : Khasi Hills. 



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



K? 



z b c d 



Fig. 33. — Plecto2yyKs jjfectosfoma, var. exserfa. 



83. Plectopylis affinis, Gude. 



riectopylis affinis, Gude, Science Gossip, n. s. iii, 1897, p. 276, 



fig. 41 (sbell 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 periphei'v, 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 tlie 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. 



Hab. Assam : Khasi Hills. 



Plectojyylis 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 



