REPORT ON THE GASTEROPODA. 97 



nacreous shell-structure, by its rounded mouth, and by its short pillar. It may be interesting to 

 observe that apparently Trochus collaris, Sow., and Trochus lecvis, Sow., both tertiary fossils from 

 Patagonia, described in the Appendix to Darwin's Geol. Observ. on South America, p. 256, and 

 that certainly Solarium rcticulatum , Phil, (see Enum. vol. ii. p. 149), a species which the " Porcupine " 

 dredged in the North Atlantic at Stations 9, 116, 17, 17a ; and probably a good many more species 

 already described, belong to this genus. 



The Solarium rcticulatum, Phil., is intermediate between Basilissa coslulata, Wats., and Basilissa 

 oxytropis, Wats. 



A. Adams's subgenus Forskdllia (Gibbula) is quite distinct. In it " the last whorl has a 

 conspicuous groove at the periphery," according to his definition ; but that is a spiral furrow formed 

 by an impressed fold of the shell-wall in each successive whorl — not a sinus in the edge of the mouth 

 resembling that in the Pleurotomidse, and differing from that of Scgucnzia in the same way as the 

 sinus of Defrancia differs from that of a typical Pleurotoma. 



Species. 



1. Basilissa lampra, Wats. 4. Basilissa alia, Wats. 



2. Basilissa simplex, Wats. 5. Basilissa superha, Wats. 



3. Basilissa munda, Wats. 6. Basilissa costulata, Wats. 



7. Basilissa oxytropis, Wats. 



1. Basilissa lampra, 1 Watson (PI. VII. fig. 5). 



Basilissa lampra, Watson, Prelim. Report, pt. 3, Journ. Linn. Soo. Lond., vol. xiv. p. 593. 



Station 246. July 2, 1875. Lat. 36° 10' N., long. 178° E. Mid-Pacific, E. of Japan. 

 2050 fathoms. Globigerina ooze. 



Shell. — Thin, white, opalescent, smooth, faintly reticulated, with a high concave spire, 

 sharp apex, acute carina, angulated umbilicus, and rhomboidal mouth. Sculpture : Smooth, 

 glossy, iridescent, with ten to twenty faint spiral threads on the upper side of the body- 

 whorl ; the last of these which joins the lip is much stronger than the others ; a little remote 

 and below is a thread forming the keel, below which, and nearer, are two other strong 

 threads ; round the umbilicus are also two strong threads ; the intermediate space on the 

 base is marked with eight to ten impressed spiral striae. The interstices of the spirals are 

 crossed by longitudinals, which are regular, fine, hair-like, but distinct and well parted ; 

 their curve on the surface below the suture shows the old sinus. On the base they are 

 radiating and are crowded and irregular, except round the umbilicus, where in the first two 

 or three striae they are very sharp and distinct. On the upper whorls both the spirals and 

 longitudinals are finer, but sharper, than they are on the last. Colour a greyish, horny, 

 translucent, opalescent white. Spire raised, with a concave outline. Apex, which con- 

 sists of the single minute embryonic whorl, is slightly exserted and sharp ; it is quite 

 smooth, but the spirals and longitudinals begin sharply immediately below it. Whorls 6^ ; 

 the earlier ones are of slow and regular increase, depressed, quite flat on their side lines ; 



1 Xa,ttCToc, shining. 



(ZOOL. CHALL. EXP. — PART XLH. 1885.) Tt 13 



