REPORT ON THE GASTEROPODA. 81 



than the rest. Longitudinals — the whole surface is close-set with these, which are crossed 

 by the spirals, than which they are broader but less sharp, closer-set, and more irregular 

 and interrupted, especially near the upper line of tubercles and near the umbilicus. 

 Colour a bluish white when alive, with a translucent calcareous layer through which 

 the nacre shines. Spire high, a little scalar. Apex small, a little flattened, with the 

 embryonic 1^ whorl barely projecting in the middle. Whorls 6-7 ; the last is of rapid 

 increase, full rounded and a little tumid; the preceding ones are a little roundedly 

 shouldered below the suture, flat on the contour, angulated at the carina, and slightly 

 contracted into the suture ; the apical whorls are simply rounded and longitudinally 

 ribbed. Suture is linear, but strongly, not acutely defined by the perpendicular rise 

 of the whorl above it and the slight sloping shoulder below. Mouth round, scarcely 

 oblique, with a translucent porcellanous edge, and pearly within. Outer Up not descending, 

 sharp ; its inner edge is bevelled outwards at the expense of the pearly layer. Pillar-lip 

 bends over the umbilicus, is a little reverted, and expands into a tooth at the intra- 

 umbilical ridge. Umbilicus funnel-shaped, wide, pervious, but narrowed within by the 

 spiral ridge. Operculum of very many narrow whorls, which on their outer edge overlap 

 as a narrow gleaming flange. H. 0'32 in. B. 0"32, least 0"28. Penultimate whorl, 0'09. 

 Mouth, height 0'18, breadth 0-18. 



This is a much larger species than Trochus {Margarita) cincrcus, Couth., from the North Atlantic, 

 much higher, much more conical, much more exquisitely sculptured, suture more impressed, base 

 more tumid and not angulated at the edge, umbilicus larger. 



Than Trochus {Margarita) amahilis, Jeffr., it is, of course, still larger, less conical, less angulated, 

 the sutural impression is not like a rounded gouged-out line as it is there, the base is not flattened, 

 and the whole style of sculpture is totally different. 



The measurements given above are taken from an almost exceptionally fine specimen from 

 Station 78. 



47. Trochus {Margarita) ceglees, 1 Watson (PL V. fig. 10). 



Trochus {Margarita) cnglees, "Watson, Prelim. Report, pt. 4, Journ. Linn. Soc. Lond., vol. xiv. p. 704. 

 Margarita cegleiis, Boll, "Blake" Dredgings, Bull. Mus. Comp. Zool., vol. ix. p. 40. 



Station 24. March 25, 1873. Lat. 18° 38' 30" N., long. 65° 5' 30" W. Off Culebra 

 Island, West Indies. 390 fathoms. Pteropod ooze. 



Habitat.— Gulf of Mexico. 287 to 888 fathoms (Dall). 



Shell— Broadly conical, high, with a very large umbilicus, ornamented with rows 

 of tubercles, carinated. Sculpture: Spirals— there is a row of small round pointed 



1 aiyXnug, beautiful. 



(ZOOL. CHALL. EXP. — FART XLII. — 18S5.) Tt 1 1 



