398 HEY. K. B00G WATSON ON THE 



narrow and very straight, the cutting away of the point of the 

 pillar being very gradual and very slightly oblique. H. T13. 

 B. 0-33. Penultimate whorl, height 0'12. Mouth, total height 

 0-58, breadth 016. 



The tubercled angulation of this species recalls faintly a similar 

 feature in P. nivalis, Lov., Norway and Britain, and P. pleleia,^ '. 

 It is slightly like P. unifasciata, Sow., from "W. Columbia, but is 

 much longer in the canal. It is very near to P. dimidiata, Broc. 

 (a Sub-Apennine Miocene species), of which there are specimens 

 (perhaps the P. Poiverii, Calcara, which Libassi holds to be a 

 variety of P. dimidiata) as slim as the ' Challenger ' species ; but in 

 Brocchi's species the keel is sharper and persists to the mouth-edge ; 

 on the same length of shell it has two whorls less ; from the suture, 

 which is not in the least impressed, the whorl, before expanding 

 to the carina, descends in a cylindrical or even slightly contract- 

 ing form ; the surface is a little roughened with slightly raised 

 threads ; the lines of growth run from the suture forward at first 

 toward the right, not, as in the ' Challenger ' species, at once to 

 the left into the sinus ; and the embryonic whorls are more 

 rounded, with a deeper suture and half a whorl fewer. It ex- 

 tremely resembles P. undata, Lam., an Eocene fossil from Grrignon ; 

 but has the spire more attenuated, the suture rather deeper, while 

 the tubercles on the keel do not, as there, become longitudinal 

 ribs, and the snout is much longer. 



8. PLEUEOTOMA (SuKCULA) HEMIMEEES, n. sp. (fyu/zfpj/S, 



halved.) 



St. 120. September 9, 1873. Lat. 8° 37' S. , long. 34° 28' W. 

 Pernambuco. 675 fms. Mud. 



Shell. — High, conical, with a small round-tipped conical apex ; 

 ribless, but with a keel beset with longish narrow tubercles. 

 Sculpture. Longitudinals — there are only fine hair-like lines of 

 growth. Spirals — about f- down each whorl is a very sharp and 

 prominent angulation, and the keel thus formed is beset by nume- 

 rous small, sharpish, narrow and elongated tubercles, which fail to 

 become ribs ; of these tubercles there are about 12 on the earlier 

 whorls, and they become more numerous on the succeeding whorls. 

 Below this keel there is a straight-lined contraction ; above it 

 there is a long, slightly concave shoulder, with a delicate row of 

 small tubercles at the top close to the suture. Both rows of 

 tubercles, but especially the upper, are very sharp and distinct on 



