MOLLTJSCA OF THE ' CHALLENGER ' EXPEDITION. 399 



the earlier whorls, but lose individuality further down the spire. 

 From the keel downwards the whorls are scored with flat rounded 

 threads. Colour pale buff, deepening somewhat up the spire, 

 glossy. Spire high, couical, the profile-lines only slightly inter- 

 rupted by the prominence of the tubercled keel. Apex : the two 

 embryonic whorls are smooth, small, conical, with a small rounded 

 tip slightly flattened down on one side. Whorls 9 (remaining), 

 short, of very regular increase, slightly concave ill the shoulder, 

 sharply angulated at the keel, and contracted into the suture 

 below. The whole base and pillar have been broken away. 

 Suture rather oblique, defined by the slight contraction of the 

 superior and inferior whorls. Mouth is broken, but the sinus is 

 broad, rounded, and deep, in consequence of the long forward 

 sweep of the pinion-like edge of the outer lip. 



This species exists only in one fragment ; but its beauty and 

 its strongly marked features make it worth notice. It extraordi- 

 narily resembles P. dimidiata, Brocchi, but is a broader shell, with 

 a coarser stumpier apex of fewer embryonic whorls, has no spirals 

 above the keel, while those below are finer ; the suture is much 

 less sunken between the keels, and there is a substantial coronet 

 of tubercles. Pleurotoma Poiverii, Calcara (a specimen of which 

 I owe to the kindness of the Abbe Brugnone), has the upper part 

 of the whorls above the keel free of spirals, and the apex is more 

 like that of P. hemimeres, but in form it is still slimmer than 

 P. dimidiata, and its sculpture otherwise is even less like. 



9. Pletjrotoma (Surcula) anteridion, n. sp. 



St. 142. December 18, 1873. Lat. 34° 4' S., long. 18° 37' E. 

 Oft' the Cape of Grood Hope. 150 fms. Sand. Bottom tempe- 

 rature 47°. 



Shell. — High, narrow, biconically fusiform, subscalar, with 

 angularly convex and longitudinally-ribbed whorls, thin, tawny. 

 Sculpture. Longitudinals — a little way below the suture is an 

 angulation where narrow, raised, oblique ribs begin ; these slope 

 from left to right ; they extend to the suture, but not to the 

 base, where they die out more gradually than they arose ; they 

 are parted by rounded hollows, which are wider than the ribs. 

 There are about nineteen of these ribs and hollows on the last 

 whorl, but fewer on each preceding one ; besides these, there are 

 very many fine hair-like flexuous lines of growth. Spirals — the 

 shoulder below the suture (the sinus-area) has a few faint 



31* 



