358 THE VOYAGE OF H.M.S. CHALLENGER. 



the sinus-area is occupied by a broadish, square, impressed furrow ; below tbis tbere is a 

 square-edged shoulder caused by the projection of the ribs at their origin ; this forms a 

 blunt but strongish keel. The rest of the whorl is covered by about 12 fine rounded 

 threads (exclusive of those belonging to the snout, which is broken) ; the two threads at 

 the keel are close-set ; the others are pretty equal and equally arranged ; on the penulti- 

 mate whorl there are about 8 of these threads. Colour dead white, probably porcellanous 

 when fresh ; the apex is buff or sandy-coloured. Spire high, scalar, conical. Apex small, 

 high, conical, with the typical straight bars above, and obliquely reticulated ones below ; 

 the two or three of the very tip are broken. Whorls 6 below the apex ; they are short 

 and broad, of slow regular increase, with a drooping slightly concave shoulder, keeled, and 

 from the keel contracting conically to the inferior suture ; the last whorl is very short and 

 small, with a rounded convexly conical base : the extreme point of the pillar and snout is 

 broken. Suture obtusely, but angularly, impressed. Mouth oval. Outer Up almost 

 semicircular, with an angle at the keel ; its edge advances very far forward below ; above 

 it forms a very deep, wide, funnel-shaped sinus close up to the suture. Inner lip slightly 

 excavated, with a very small border. H. 0"36 in. B. 0"13. Penultimate whorl, height 

 0'06. Mouth, height 0"1, breadth 0'08. (These measurements are of necessity, from the 

 broken state of the mouth, somewhat hypothetical ; but they are at least not exaggerated.) 



12. Clathurella chyta 1 (Watson), (PI. XVIII. fig. 4). 



Pleurotoma (Defrancia) chyta, Watson, Prelim. Report, pt. 10, Journ. Linn. Soc. Lond., vol. xv. 



p. 466. 



Station 73. June 30, 1873. Lat. 38° 30' N., long. 31° 14' W. West of Azores. 

 1000 fathoms. Pteropod ooze. Bottom temperature 39° - 4. 



Shell. — White, conical, ribbed, with a high, subscalar, small-pointed apex, a short 

 tumid body-whorl, a rounded contracted base, and a small snout. Sculpture: Longi- 

 tudinals — there are on the last whorl 14 ridge-shaped, round-topped, curved, oblique ribs: 

 they are not strong, originate in small rounded beads at an angulation below the sinus- 

 area, and die out on the base : they are parted by shallow rounded furrows of double their 

 breadth ; on the first regular whorl they appear as simple beads 9 in number ; on the 

 next whorl they assume the form of straight riblets, whose obliquity increases on each 

 successive whorl : the lines of growth, which are quite independent of the riblets, are 

 very slight. Spirals — there is a row of quite separate, very small, elongated tubercles 

 below the suture : the sinus-area is bordered on its lower side by a very faint and small 

 furrow : the angulation of the whorl below this is chiefly due to the row of beads in which 

 the ribs originate, and here there are several very minute threads ; 9 somewhat stronger, 

 equal, and equally parted threads occupy the body from this angle downwards ; about 5 



1 x VT °>> cas t- 



