170 THE VOYAGE OF H.M.S. CHALLENGER 



the body at a right angle, and is right-angled at the keel. Inner Up is slightly concave 

 above, straight on the very short pillar, and oMique down the edge of the long canal ; a 

 thin narrow glaze lies on the edge of the body and pillar, at the point of which it crosses 

 and lies hidden behind the sharp canal-edge. H. 0'45 in. B. 0'2. Penultimate whorl, 

 height 0-08. Mouth, height 0-28, breadth 0D9. 



This pretty little species perhaps resembles Trophon barvicensis, Johnston, more than any other, 

 but, besides being more attenuated, is markedly differentiated by the median angulation of the 

 whorls and the absence of the spiral threads of that species. 



8. Trophon septus, Watson (PL X. fig. 11). 



Trophon septus, Watson, Prelim. Report, pt. 14,'Journ. Linn. Soc. Lond., vol. xvL p. 391. 



Station 149d. January 20, 1874. Lat. 49° 28' S., long. 70° 13' E. Eoyal Sound, 

 Kerguelen. 28 fathoms. Volcanic mud. 



Shell. — Thin, porcellanous white, club-shaped, with a low scalar spire, blunt apex, 

 high-shouldered sharply expressly and spinously keeled whorls, a tumid body, and a long 

 thin flexuous snout. Sculpture : Longitudinals — the whorls are scored by feeble lamellae 

 and by coarsish lines of growth. Spirals — at the top of each whorl, but separated from 

 the suture by a broad tabulation, is a right-angled keel, from which, nearly parallel to 

 the axis of the shell, project a series of hollow, vaulted, compressed triangular spines ; l 

 besides this coronal there is no other spiral sculpture except some irregular lines on the 

 base. Colour porcellanous white, with some chalkiness on the surface. Apex rather 

 small, mamillate, and a little turned down on one side. Whorls 5 or 6, flatly tabulated 

 above, with a rectangular keel, below which they are cylindrical ; the last is a little tumid 

 on the base, which contracts rapidly and is drawn out into a long, thin, flexuous snout. 

 Suture almost rectangular. Mouth round, with a blunt angle at the top and a siphon at 

 the keel, and suddenly prolonged into the narrow canal. Outer Up sharp, thin, direct, 

 well arched, not prominent. Inner Up is concave above, slightly oblique on the very 

 short pillar, and much more so on the long, bent, and slightly reverted snout ; a thin 

 narrow glaze defines it to the point of the pillar, where it crosses to the canal, leaving a 

 minute chink on its outer edge above. Operculum thin, yellow, oval, with a blunt apex, 

 where the nucleus is terminal. H. - 91 in. B. 0"43. Penultimate whorl, height O'l. 

 Mouth, height 0-67, breadth O'l 6. 



The upturned coronal of hollow spines and the more contracted base differentiate this from 

 Trophon goodridgii, Forbes. It has some faint resemblance to the Plcurotoma cedo-nulli, Eeeve. 



1 These form a sort of fence — whence the name. 



