155 



NEW LAND-SHELLS FROM NEW ZEALAND. 



By Henry Sutek. 



Read ISih May, 1904. 



Rhytida duplicata, n.sp. 



Shell convexly depressed, umbilicated, carinated, with a ridge above 

 the keel. Sculpture : The surface of the shell is rather irregularly 

 and rugosely plicated, the plicae, by anastomosing, forming a partial 

 network, and inclined backward in the same direction as the incre- 

 mental lines, which are at intervals more or less conspicuous on the 

 last whorl. Colour: My specimens being all so-called ' dead shells,' 

 and having lost the epidermis, it is impossible to describe the colour. 

 To judge from analogy, I suppose it to be about the same as in 

 R. Greenwoodi. The spire is depressed conoidal, slightly convex, obtuse. 

 The apex is slightly raised, obtuse, of 1^ whorls, and finely obliquely 

 plaited. The embryonic shell is subglobose, having the upper side flat 



and the umbilicus shallow. Diam. 3-5, height 2-5 mm. "Whorls 4J, 

 rapidly increasing, the first ones convex, the last bluntly keeled at 

 the periphery, above which, at a distance of about 2 mm., is a revolving 

 rib, separated from the keel by a shallow groove, and from the slightly 

 raised ridge below the suture by a broad depression; this ridge 

 disappears gradually on the penultimate whorl. Base flatly convex. 

 Suture shai"ply impressed, near the aperture subcanaliculate. Aperture 

 obliquely transverse, subtriangular, the margins slightly approximating 

 and united by a callus on the penultimate whorl. Outer lip sharp, 

 slightly depressed and advancing above, angled at the periphery and 



