144 HELICIDjl. 



proportion to the diameter ; in the last whorl not widening 

 suddenly at the aperture, and in the lower side sloping from the 

 periphery to the umbilical angulation ; the right margin of the 

 peristome is depressed ; the umbilicus is deeper, and the hori- 

 zontal median parietal fold does not quite reach the apertural 

 ridge. The shell is darker in colour and more strongly ribbed. 



Major diam. 19, minor 15 mm. ; alt. 7 mm. 



Hob. Burma : Moulmain. 



The variety obesa is darker in colour than the type, being of a 

 fuscous chestnut. It is more compressed and distinctly ribbed ; 

 the shell is higher in proportion to the diameter, and the umbilicus 



c 

 Fig. 75. Plectopylis bensoni, var. obesa. 



is deeper ; the last whorl does not widen suddenly, and the right 

 margin of the peristome is depressed, the aperture being conse- 

 quently somewhat ear-shaped; the lower side slopes from the 

 peripheral region to the umbilical angulation. The armature 

 does not differ materially from that of the type, except that the 

 median horizontal parietal fold does not quite reach the apertural 

 ridge. Six specimens were received by me from the late Miss 

 Linter, five of these being more or less decorticated. 



Var. venusta, Gude. 



Plectopylis achatina, var. venusta, Gude, Science Gossip, N. s. v, 

 1898, p. 134, fig. 85. 



Differs from the type and the other varieties in being smaller. 

 It resembles the variety obesa in the deeper umbilicus, in the 

 sloping underside, in the comparative height of the shell, and in 

 the median parietal fold not reaching the apertural ridge, but the 

 last whorl widens more, as in the type. In colour it is pale 

 yellowish-white, flammulated with chestnut above and at the side. 

 The peristome is livid brown, the left margin paler, the right 

 margin a little depressed. 



Major diam. 17, minor 14 mm. ; alt. 7 mm. 



Hob. Burma. 



The variety venusta is smaller than any form of P. bensoni I 

 have seen. It is pale yellowish-white in colour, flammulated with 



