228 PROCEEDINGS OF THE MALACOLOGICAL SOCIETY. 



the last whorl is very acutely carinate, not descending ; aperture sub- 

 lunate, the peristome being somewhat thickened, very pale horn 

 colour, and slightly reflexed over the umbilicus. Diam. max. 39"5, 

 alt. 19'5 mm. 



Related to D. Maarseveeni (Bock), but the present shell is larger, 

 darker in colour, the sculpture is stronger, and the rib-strise are sub- 

 granular. 



Dyakia euconus, n.sp. Fig. 1. 



Shell sinistral, well elevated, trochiform, very narrowly umbilicated, 

 somewhat thin, the earlier whorls brown horn colour, and the later 

 whitish beneath a horn-coloured periostracum, slightly paler below ; 

 the first two whorls are smooth save for traces of I'adiate wrinkling at 

 the sutures, then a large number of closely-set fine spirals appear, 

 cutting irregular and obscure lines of growth, these lines of growth 

 gradually become stronger and the spirals less conspicuous ; the 

 sculpture below is spirals cutting irregular lines of growth; a few 

 specimens show traces of a ridge at the periphery such as is to be 

 seen in D. granaria ; whorls 6, regularly and moderately increasing, 

 somewhat convex, with a well-marked suture, the last whorl rounded 

 at the periphery in adult shells; aperture subquadrate, the peristome 

 somewhat thickened and slightly reflexed over the umbilicus. Diam. 

 max. 36, alt. 24 mm. 



Noteworthy for its trochiform shape, with somewhat convex whorls ; 

 the sculpture is not striking until viewed under a lens. I have seen 

 three specimens, constant in their characters, and all appear to have 

 sustained slight injuries during life. 



