MOLLTJSCA OE THE ' CHALLENGER ' EXPEDITION. 405 



series of about 20 (on the penultimate whorl about 5) pretty 

 equal rounded threads and furrows — the first is weaker than the 

 rest ; the second occupies the edge of the shoulder, and marks 

 the angulation of the whorls there rising (as does also the next 

 thread below) into special prominence in crossing the ribs ; 

 towards the extreme point of the shell, beyond the threads above 

 referred to, are three or four smaller closely crowded threads. 

 Colour white. Spire high conical, scalar. Apex broken (but 

 probably blunt and Mcmgelia-Yike). Whorls below the embryonic 

 ones 6-7, of slow and regular increase, short and broad, high but 

 small shouldered, prominent above, and a little contracted below; 

 the last contracts from the keel and forms a perfect cone on to 

 the extreme point. Mouth 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. 

 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 Mangelia. 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, P. mitrceformis, Wood, and P. 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. 



14. Plettrotoma (G-enota) engonia, n. sp. (eyycovios, an- 

 gular.) 



(?) St. 169. July 10, 1874. Lat. 37° 34' S., long. 179° 22' E. 

 N.E. from New Zealand. 700 fms. Grey ooze. Bottom tempe- 

 rature 40°. 



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

 Off Inosima, Japan. 345 fms. Sandy mud. Bottom tempera- 

 ture 41°-1. 



Shell. ^- Fusiform, biconical, with an expressed rounded keel 

 angulating the whorls, and a broad, prominent, lop-sided snout. 



