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



Shell. — High, narrow, and conical, with very short whorls, of which there are 6 ; the 

 last whorl exceptionally small, with a short conical base and very small snout ; the suture 

 very slight, but extremely oblique ; the apex blunt and rounded ; there are narrow, high, 

 rounded, curved, and very oblique ribs, which run continuously from the apex to the point 

 of the base, but not to the snout ; there are obsolete spiral striae, which become stronger 

 on the point of the pillar. H. 0-19 in. B. 0*067. Penultimate whorl, height 0-033. 

 Mouth, height 0-078, breadth 0"033. 



The specimen of this very marked species is in too bad condition for more minute description. 

 It is very like Fleuivtoma (Drillia) exilis, Pease, but is much more attenuated, and the last whorl is 

 much shorter. 



73. Pleurotoma {Mangelia) acanthodes, 1 "Watson (PI. XXIII. fig. 3). 



Pleurotoma (Mangelia) acanthodes, Watson, Prelim. Eeport, pt. 9, Journ. Linn. Soc. Lond., vol. xv. 



p. 433. 



Station 56. May 29, 1873. Lat. 32° 8' 45" N., long. 64° 59' 35" W. Off Bermuda. 

 1075 fathoms. Coral mud. Bottom temperature 38°"2. 



(?) Station 75. July 2, 1873. Lat. 38° 38' N., long. 28° 28' 30" W. Fayal, Azores. 

 450 to 500 fathoms. Volcanic mud. 



Shell. — High and narrow, biconical, ribbed and spiralled, of a frosted-white colour, 

 with subscalar, blunt but small-pointed spire, a small body-whorl and mouth, and rather 

 contracted base. Sculpture: Longitudinals — on the last whorl there are 14, on the 

 penultimate 10, and on the first regular whorl 9 ribs : they arise very feebly at the suture, 

 gain height in the sinus-area, and add on a little breadth below ; they are high, narrow, 

 and rounded ; toward the mouth they are crowded, but in general are parted by rounded 

 furrows of two or three times their width ; they extend to the extreme point of the base, 

 but not to the snout. The whole surface is likewise fretted with minute sharp lines of 

 growth. Spirals — on the embryonic whorls there is one, on the other whorls two, fine 

 spiral threads ; the upper and stronger lies below the sinus-area about one-third down the 

 whorl, and forms, with help of an angulation at that point, a rather sharp keel, rising into 

 small sharp tubercles at the intersections of the ribs ; between this keel and the root of 

 the snout there are on the last whorl six weaker threads, which all rise into tubercles as 

 they cross the ribs. On the snout are three or four weaker threads without tubercles : 

 the interstices of these spirals are from twice to four times their width. The whole 

 surface of the shell, except the embryonic whorls, is scored with very fine, sharp, close-set 

 spirals, which, at crossing the lines of growth, are beset with microscopic blunt prickles 

 which give the frosted aspect to the shell. Colour white ; only the tip is smooth. Spire 



1 dxavQudqg, prickly. 



