96 



HELICID^E. 



obliquely, their posterior extremities dilated, almost bifurcated ; 

 the fifth also descending a little, its posterior termination 

 suddenly deflected ; the sixth, horizontal, with a minute denticle 

 above, and an elongated one a little farther back, below the 

 posterior termination of the fold (see fig. 41 g, which shows the 

 inside of the outer wall of the shell). The figures are from 

 the type specimens in the collection of Lt.-Col. God win- Austen, 

 who obligingly lent them to me for this purpose. 



Figs. 41 a-c are of natural size, while figs. 41 d-g are enlarged ; 

 e shows the armatures from the anterior and / from the posterior 

 side, while g exhibits the inside of the outer shell-wall with the 

 palatal barriers in situ. 



91. Plectopylis nagaensis, Godwin-Austen. 



Helix (Plectopylis) nagaensis, Godwin-Austen, P. Z. S. 1874, p. 609, 



pi. 73, fig. 4 (armature). 

 Helix (Atopa (Plectopylis}} nagaensis, Tryon, Man. Conch, ser. 2, 



iii, 1887, p. 161, pi. 35, figs. 78, 79. 

 Plectopylis nagaensis, Pilsbry, Man. Conch, ser. 2, ix, 1894, p. 146 : 



Gude, Science Gossip, N. s. iii, 1897, p. 206, fig. 33 (shell aud 



armature). 

 Plectopylis (Chersaecia) nagaensis, Gude, op. cit. vi, 1899, p. 148. 



Original description. " Shell sinistral, widely umbilicated, 

 discoid, dull ochry-brown, epidermis thick and coarsely striate ; 

 above depressedly pyramidal. Whorls 7, flat, narrow, and those 

 near apex closely wound, the last very descending near mouth. 

 Aperture diagonal, broadly lunular, outer margin well rounded, 



Fig. 42. Plectopylis nagaensis. 



peristome very thick, white, reflected. A thick ridge on the 

 parietal side, separated by slight indentations, connects the 

 inner margins ; and from the middle of this runs back a 

 long horizontal lamella, terminating close to, but not connected 

 with, the single vertical lamina ; this is thick and bifurcate below, 

 tapering above and curving backwards ; a short free lamella is 



