PLECTOPYLIS. 143 



inspection a specimen measuring 21 mm. in diameter, and four 

 immature shells, in various stages of growth, all showing sets of 

 barriers similar to that of the immature Plectopylis bensoni shown 

 in fig. 71 a. 



Var. castanea, Gude. 



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

 1898, p. 134, fig. 86. 



Differs from the type in being smaller in diameter and pro- 

 portionately higher ; it is darker in colour, being blackish-brown 

 above and a little paler below. It resembles the variety obesa in 

 being more rounded in outline, in the last whorl not widening 

 suddenly at the aperture, in the sloping underside, and in the 

 median parietal fold not reaching quite to the apertural ridge ; 

 the last 2^- whorls are more strongly decussated above and below 

 than in any other form. An obsolete keel is visible at the 

 periphery. 



Major diam. 21, minor 19 mm. ; alt. 8 mm. 



Hab. Burma. 



The variety castanea is darker than the other forms of P. bensoni 



c 

 Fig. 74. Plectopylis bensoni, var. castanea. 



except the variety infrafasciata, being of a blackish-brown above, 

 a little paler below. It is, however, larger than that variety, and 

 does not possess the white band below ; the umbilicus is also 

 much deeper, the shell being in that respect more like the variety 

 obesa, which it also resembles in the sloping underside ; the 

 aperture is proportionately larger than in that variety. The 

 spiral lines on the last 2^ whorls are visible without the aid of a 

 lens. The specimen figured was received by me from the late 

 Miss Linter. ' 



Var. obesa, Gude. 



Plectopylis achati 

 p. 115, fig. 83. 



Differs from the type in being more compressed and higher in 



Plectopylis achatina, var. obesa. Gude, Science Gossip, N. s. v, 1898. 

 p. 115, fig. 83. 



