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



long and narrow, with parallel sides. Outer lip forms a right angle almost close up to 

 the body, and just at this point forms a very slight shallow open sinus ; below this it 

 advances straight to the extreme point of the shell. Inner lip is very slightly concave ; 

 a thin layer of glaze crosses the body, but becomes thicker, with a prominent edge, down 

 the pillar, which at its point is twisted, but is hardly oblique. H. 0'38 in. B. 0"13. 

 Penultimate whorl, height 0-05. Mouth, height 0'2, breadth, 0-04. 



The destruction of the apex in this specimen is unfortunate ; but the form of the shell suggests 

 a tip blunt, rounded, and short, as in Mangclia. The Messrs Adams have defined their subgenus 

 Genota as having a deep posterior sinus, a feature which should exclude this species from the group; 

 but since the only two species, Plcurotoma mitrarformis, Wood, and Plcurotoma papalis, Reeve (if they 

 be two), which they quote as types of the subgenus, have both a very slight sinus remote from the 

 suture, the present species may be put along with these. 



28. Pleurotoma (Genota) engonia, Watson 1 (PL XX. fig. 7). 



Plcurotoma (Genota) engonia, Watson, Prelim. Report, pt. 8, Journ. Linn. Soc. Lond., vol. xv. p. 405. 



(?) Station 169. July 10, 1874. Lat. 37° 34' S., long. 179° 22' E. North-east from 

 New Zealand. 700 fathoms. Blue mud. Bottom temperature 40°. 



Station 232. May 12, 1875. Lat. 35° 11' N., long. 139° 28' E. Off Inosima, 

 Japan. 345 fathoms. . Green mud. Bottom temperature 41 'l". 



Shell. — Fusiform, biconical, with an expressed rounded keel angulating the whorls, 

 and a broad, prominent, lop-sided snout. Sculpture : Longitudinals — there are no ribs. 

 The lines of growth are strong, hair-like, unequal, and close-set ; on the keel which marks 

 the line of the old sinuses they are exceptionally strong, prominent, regular, and a little 

 remote, as they also are at the top of the whorls in the suture ; still they are throughout 

 rounded, not sharp. Spirals — the whorls are angulated about the middle, and pro- 

 ject in a rather narrow, prominent, rounded keel, which is almost crenulated by the 

 lines of growth. The whole surface is also covered by small, broadish, rounded, close- 

 set spiral threads, which on the base are somewhat granulated. On the left side 

 of the point of the snout they tend to become obsolete, as they also do on the earlier 

 regular whorls. Colour porcellanous white. Epidermis: only one minute fragment 

 remains, which seems thin, yellowish, and membranaceous. Spire high, subscalar, typi- 

 cally conical, the profile-lines being very little interrupted by the carinal projection. 

 Apex blunt, rounded, consisting of two smooth globular whorls. Whorls 8, short, broad, 

 of regular increase, the last rather large ; they have a sloping, slightly concave shoulder ; 

 their profile below the keel is straight and scarcely contracted. At the top of each whorl 

 there is a slight collar, which gives the effect of a very slight canaliculation to the suture. 



II lyyuiiioc t angular. 



