12 OR. NELSON ANNANDALE ON 



which it is exserted differs iu different individuals, but it is never 

 so long as that of P. yyolita or P. conica, or so short as that of most 

 forms of P. turbinis. The upper surface of all the whorls is 

 slightly, obliquely flattened, but they are never angulate or carinate. 

 The suture is impressed. The body-whorl is broad but oblique. 

 The mouth of the shell is large and a little less than twice as high 

 as broad, but the upper extremity is separated from the upper marg- 

 gin of the body- whorl by a distance considerably greater than the 

 height of the spire. The main axis of the mouth forms an acute 

 angle with that of the shell. The peristome is continuous and the 

 callus well developed, but not prominent, in complete shells. The 

 upper extremity of the lip is thickened at its junction with the 

 shell and there is a rather broad thickened ridge just inside its 

 outer margin, which is itself sharp. The lower or anterior margin 

 is very little expanded or everted. The shell is narrowly umbilicate 

 and the expanded callus is reflected over the umbilicus. 



The external surface is not strongly polished. It is sculptur- 

 ed with numerous fine, low, close-set longitudinal ridges, some of 

 which (set apart at fairly regular intervals) have a broader and 

 flatter appearance than the others. The ridges are crossed by still 

 more numerous minute, decussate or guttate spiral striae, and the 

 surface has a distinctly sculptured look to the naked eye, at any 

 rate on the body-whorl. 



The external colour is uniform olivaceous, in some shells 

 with a rather pale greenish and in others with a dark almost 

 purplish tint. The internal surface is greenish white in pale shells 

 and the periphery is faintly stained with pale yellow, the lip being 

 sometimes very narrowly bordered with black. Darker shells are 

 deep purple internally, with a faint indication of spiral bands, which 

 are probably quite visible in young shells. Adult shells of this 

 type have a broad white border to the lip and columella. 



The operculum is thick and heavy. Its outline is irregularly 

 pyriform, the external margin being strongly convex and the upper 

 part of the inner margin deeply concave. The posterior extremity 

 is bluntly pointed. The external surface is irregularly concave as a 

 whole, and has the growth lines delicate but distinct. The 



JOUKN. NAT. HIST. S0C. SUM. 



