REPORT OX THE GASTEROPODA. 59 



of the shell ; each whorl round its base is keeled by a stronger prominent triangularly 

 acute substellately tubercled thread ; above this lies another thread a little stronger and 

 more prominent than the normal spiral threads above ; between these two stronger threads 

 is a small shallow furrow, which is perpendicularly (not obliquely) striate ; round the base 

 and within the carinated periphery is another obtuse-angled, tubercled keel ; on the base 

 are some 18 or 20 flattened threads; towards the rim these are very feeble, and are not 

 very distinguishable from the 2 or 3 weaker threads which occupy the wide intervals 

 between ; towards the middle space of the base the stronger threads become more marked 

 and also faintly tubercled, the interstitial ones tend to disappear ; close in to the pillar, 

 however, some very faint threads again appear in the interstices. Colour pale ruddy, 

 with some suffused deeper spots, and flecked on the tubercles with rich bright chestnut. 

 Spire conical, with straight profile lines. Apex rather large, blunt, and coronated ' by 

 the prominence of the carinal tubercles ; it is rather strongly radiatingly striated ; the 

 extreme tip is very minute and is immersed ; it is rough, not polished or glossy. Whorls 

 in all 9, of very regular but somewhat rapid increase ; they are flatly conical, being 

 neither convex nor concave ; the last is largish, and is very sharply angulated at the 

 periphery. Suture linear, and only recognisable from the projecting keel above it. Mouth, 

 largish, quadrangular. Outer lip thin, flat on the side and on the base, acute-angled at 

 the periphery. Pillar is broken in front, but seems short ; it is encompassed with a pad 

 of nacre and has a twist on it; there is no approach to an umbilicus. H. 1 in. B. 0"95. 

 Penultimate whorl, height 0"28. Mouth, height, 0.3. Breadth (from angle to angle) 0"5. 



In general character this is like Troclms mcyeri, Phil. = Trochus Icevis, Homb. and Jacq. (Voy. 

 au pole sud, Zool., vol. v. p. 56, pi. xiv. figs. 17, 18), but that shell is in colour brown, and the 

 stains are arranged in narrow divergent lines, not, as here, in ruddy stains affecting especially the 

 tips of the tubercles. In that species, the whole whorl swells out below the suture, not, as here, the 

 mere thread, nor in that species are the tubercles there any larger than elsewhere. The threads on 

 the sides are fewer, and their tubercles are larger ; on the base the threads are much coarser and 

 are more strongly tubercled ; the entire apex is dark coloured, and is smaller and smoother. 



17. Trochus (Ziziphinus) stirophorus,- Watson (PI. VI. fig. 2). 



Trochus (Ziziphinus) stirojjhorus, Watson, Prelim. Report, pt. 4, Journ. Linn. Soc. Lond., vol. xiv. p. 695. 



Station 24. March 25, 1873. Lat. 18° 38' 30" N., long. 65° 5' 30" W. Off Culebra 

 Island, West Indies. 390 fathoms. Pteropod ooze. 



Shell. — Small, conical, scalar, inflated on the base ; whorls angulated, with three strong 

 carinas near the periphery, white over nacre. Sculpture: Spirals — at the periphery is a 

 sharp flange-like carina ; above this, about one-third of the distance to the suture, is a 

 second, almost equally strong and prominent, which forms a shoulder to the whorls. The 



1 Hence the name. ~ cnTget, a keel ; f ofsTv, to have. 



