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



apex is strongly suggestive of Clathurella ; but the shape of the apex is blunter than is characteristic 

 of that group, while the ornamentation is not really reticulate. 



It has some general resemblance to Phurotoma torquata, Phil. ; but the sculpture is more deli- 

 cate, and the spire is stumpier than in that species, which has also a sharp-pointed yellow apex with 

 true Clathurella reticulated ornamentation. 



67. Pleurotoma (Plewotomella) papyracea, Watson (PI. XX. fig. 5). 



Pleurotoma (Thesbia) papyracea, Watson, Prelim. Report, pt. 9, Journ. Linn. Soc. Lond., vol. xv. 



p. 450. 



Station 147. December 30, 1873. Lat. 46° 16' S., long. 48° 27' E. Between Prince 

 Edward Island and the Crozets. 1600 fathoms. Diatom ooze. Bottom temperature 

 34°-2. 



Shell. — Thin, like delicate tissue-paper, white, bluntly keeled, subplicate, with a small, 

 hio-h, sharp, scalar spire, an angulated suture, a short tumid body-whorl narrowing from 

 the carina, suddenly contracted on the base, and prolonged into a largish triangular one- 

 sided snout. Sculpture : Longitudinals— there are extremely fine hair-like lines of growth; 

 there are also oblique, rounded, narrow foldings of the surface, which below the sinus-area 

 rise into 14 small, narrow, sparse ridges or elongated tubercles and extend to the base: 

 on the earlier whorls these rise into small thread-like ribs which reach the inferior suture. 

 Spirals — the almost membranaceous sinus-area forms a sloping shoulder below the suture, 

 and occupies about one- third of the whorl ; below this is the keel, on which the little 

 tubercles rise : from this keel downwards the surface is covered with minute, unequal, but 

 rather regular, though somewhat interrupted, sparse threads with broader intervals : 

 besides this there is a microscopic, obsolete, spiral granulation which extends to the 

 sinus-area. Colour alabaster-white, so far as the excessive thinness permits ; the small 

 spiral threads are somewhat dead white ; the embryonic whorls are of a rich ruddy-orange 

 tint. Spire perfectly conical, scalar, high, sharp. Apex consists of 3^ ruddy, smooth, 

 embryonic whorls, which are globose, divided by an impressed suture, and rise to a small, 

 blunt, round top, in the middle of which the extreme tip just barely rises into sight. 

 Wwrls 8^ in all, of slow, but increasingly rapid enlargement; those of the spire are 

 rather narrow and high, and have a high flat shoulder, a sharp angulated keel, and a very 

 slight contraction from this point to the inferior suture ; the last whorl is tumid, but 

 short, with a sloping shoulder, a much blunter angulation, a marked contraction from this 

 point, a very blunt angulation defining the base, which contracts a good deal and suddenly, 

 and which on the right side is prolonged into the conical, triangular-shaped, blunt though 

 small-pointed snout. Suture linear and almost invisible, but well defined by the angula- 

 tion at which the whorls meet, and also by the change of colour where the inferior whorl 

 laps up on the one above it, which produces a pseudo-margination. Mouth large and 



