470 GASTROPODA. [PectinibrancMri. 



square-cut, and narrower than the ribs ; the last whorl with 10 ribs 

 and a number of minute threadlets upon the back of the canal, added 

 to which are the oblique lines of old beaks ; grooves and ribs 

 subequal, but the former sometimes broader as they proceed ante- 

 riorly. The growth-striae aie minute, slightly irregular in strength, 

 and giving in places (usually upon the upper whorls of the spire) a 

 slightly clathrate appearance. Colour of fresh specimens light horn, 

 dead shells greyish-white. Spire high, gradate, turrieulate, with an 

 obtuse rounded apex, a little higher than the aperture with canal. 

 Protoconch of about 2 convex turns, slopingly shouldered, with minute 

 spirals, the precursors of the adult sculpture : nucleus central, de- 

 pressed globular, smooth. Whorls 7, flattened, strongly shouldered 

 at the suture, first slowly then more rapidly increasing. Suture deep, 

 margined above on the lower whorls. Aperture elongate, somewhat 

 narrow, slightly contracted in front and forming a short open canal, 

 which is truncated and slightly sinuate at the base, bent backward 

 and a little to the left. Outer lip slightly thickened, descending with 

 a light downward sweep, crenulate at the margin ; the sinus indis- 

 tinct, situated on the upper cingulum. Columella excavated in the 

 middle, drawn out to a point on approaching the anterior beak. Inner 

 lip forming a broad callus, through which on the parietal wall the 3 

 cinguli appear as folds, with a distinct edge, which is slightly raised, 

 connected above with the outer lip. 



Diameter, 5-75 mm. ; height, 15-7 mm. 



Animal unknown. 



Type in the Dominion Museum, Wellington. 



Hob. Off Great Barrier Island, in 110 fathoms. 



Remark. This species is in its sculpture nearly allied to T. septem- 

 Urnta and trilirata, Harris, from the Eocene of Australia. 



2. Turns ischna, Watson, 1881. Plate 21, fig. 2. 



Pleurotmna ischna, Watson, J.L.S., xv, 1881. 403 : Chall. Rep., xv, 280, 

 pi. 22, f. 2 ; P.L.S. N.S.W., x, 116 ; T.N.Z.I., xxxi, 65 ; Index, 70. 



Shell high, narrow, conical, blunt, with a contracted base and 

 longish canal, little sculpture, strongish, yellowish-grey, porcellanous. 

 Sculpture : Longitudinals there are only strongish unequal lines of 

 growth, which rise into small tubercles, especially on the upper whorls ; 

 between the stronger lines the surface of the shell is delicately fretted 

 with other minute sharp lines. Spirals the whorls are faintly keeled 

 above the middle by a spiral thread, which is a little stronger and more 

 prominent than any of the others ; close above the suture is another 

 almost as strong, and which also slightly carinates the whorls ; half- 

 way between these is a finer thread, which tends to split into 2 very 

 fine threads ; at the suture, but visible beyond the aperture, is another 

 thread, which here defines the base. The longitudinals rise into very 

 small tubercles as they cross the spirals ; but this feature is much 

 stronger on the upper whorls, which are reticulated ; on the last whorl 



