28 G THE VOYAGE OF H.M.S. CHALLENGER. 



15. Pleurotoma (Surcula) staminea, Watson (PI. XX. fig. 3). 



P/curotoma (Surcula) staminea, Watson, Prelim. Report, pt. 8, Journ. Linn. Soc. Lond., voL xv. 



p. 388. 



Station 146. December 29, 1873. Lat. 46° 46' S., long. 45° 31' E. Off Marion and 

 Prince Edward Islands. 1375 fathoms. Globigerina ooze. Bottom temperature 35 0, 6. 



Station 149j. January 29, 1874. Lat. 48° 43' S., long. 69° 15' E. Off Cumberland 

 Bay, Kerguelen. 105 fathoms. Volcanic mud. 



Shell. — High, narrow, biconically fusiform, scalar, carinated, with spiral threads, thin, 

 white. Sculpture: Longitudinals — the shell is scored with coarse irregular sinuous 

 lines of growth, but there is no trace of any other longitudinal markings. Spirals — 

 above the middle of each whorl is a strong carination only slightly projecting, but marked 

 by the angulation of the whorl and by the prominence of the thread on its crest. On the 

 body-whorl there is a tendency to a second carination, which runs into the mouth just 

 below the junction of the outer lip, and is thus concealed on all the earlier whorls (it is 

 evident that this inferior anp-ulation is a feature which varies much in different indi- 

 viduals). Besides these, the whole surface is covered with irregular and unequal threads ; 

 these are feeblest on the sloping shoulder below the suture ; close below the upper keel 

 and on the snout and its conical base they are fine ; about 4 above and 2 below the 

 lower keel are the strongest, but they all tend to subdivide themselves ; and the whole 

 shell is scored by irregular and somewhat broken microscopic lines. Colour translucent 

 white under a thin, pale, greyish-yellow epidermis, which adheres closely, but is apt to 

 rub through. Spire is high, narrow, conical, and slopingly scalar in consequence of the 

 drooping shoulder between the suture and the keel. Apex is more or less eroded in all 

 the four specimens : it consists of not more than 1^ embryonic whorls, which are globose, 

 smooth, and with the point a little obliquely pressed down. Whorls 8^, rather short 

 except the last, of regular increase, angulated above the middle ; the shoulder between 

 the suture and the keel is straight-lined. From the keel the whorls are slightly con- 

 tracted to the inferior suture, and the profile-line here is scarcely convex. The last whorl 

 is feebly tumid below the keel, and is drawn out from a produced conical base into a long, 

 narrow, cylindrical, very slightly upturned snout, which projects on the right side of the 

 base. Suture a fine, sharp, slightly irregular line, well defined by the contraction of the 

 whorl above and the straight line of the shoulder on the whorl below. Mouth club- 

 shaped, being oval above, and prolonged below into a long, but not very narrow, canal, 

 which is a little sinuous, and widens towards its end in consequence of the oblique 

 cutting away of the pillar-lip. Outer lip, which is thin, sharp, and patulous, leaves the 

 body at a right angle and advances quite straight to the keel, above which lies the deep, 

 thin-lipped, U-shaped sinus, whose lower margin runs parallel to, but a Httle above, the 

 carinal thread ; from the keel the lip-edge advances with a long, free, forward curve and 



