MOLLUSCA EAST OB' CAPE UYKON. 



51 



Ckkitiiiopsis halli(;axi, Kp. nor. 



(Fig. 16). 



Shell small, slender, elongate-conical, pale yellow, the upper rib 

 on each whorl white. Whorls twelve, incliuUng a three-whorled 

 protoconch. .Sculpture, on the first adult wliorl, two, on the 

 following three, and on the last four, sharp pi'oject- 

 ing spiral keels. The third or anterior keel of the 

 spire whorls is larger than the others, and is 

 sepai-ated from them by a broader sjjace than in- 

 tervenes between the first and second. The fourth 

 keel of the body whorl reappears on a few of the 

 preceeding whorls as a small supersutural thread. 

 Fine radial strife cross the grooves between the 

 keels. The protoconch is smooth, with whorls 

 bulging in the middle like that of C. turbonilloidet<. 

 Aperture quadrate, canal short. Base rounded. 

 Length, 5-6 mm.; breadth, 1-4 nnii. 



A single specimen. 



The species is related to C imrpihrea, Angas, 

 but differs by being half the size, more conical in 

 outline, with closer ribs, round base, and different 

 colour. 



Ficr. 16, 



Cerithiopsis 



haUif/aiii. 



PsKUDORISSOIXA ELEOAXS, sp. 7(.rn\ 



(Fig. 17). 



Shell minute, glassy translucid, tapering. Whorls six, and an 

 involute tilted protoconch. Below the 

 suture appears an opaque flattened zone, 

 defined by a revolving groove. The zone 

 grows narrower with the increase of the 

 whorls. Aperture effuse, pyriform ob- 

 lique, peristome slightly thickened and 

 incurved, outer lip retreating to tlie 

 suture. A callus is spread on the pre- 

 ceeding whorl. Behind the columella 

 is a minute umbilical crevice. Length, 

 3-15 mm.; breadth, 1-15 mm. 



Several specimens were taken. This 

 species is a northern representative of 

 P. tasmanica than which P. elpgans is 

 a third smaller, but has an extra whorl, 

 tapers more rapidly, and has the sub- 

 sutural stricture more defined. 



Ficr. 17. 

 Pneudorissoina elegans. 



