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



Habitat. — North Atlantic. "Valorous," Station 12, 1450 fathoms; Station 13, 690 

 fathoms ; Station 16, 1785 fathoms ; in " Porcupine," in 1869, Stations 13, 16, 17, 42, 47, 

 from 208 to 1230 fathoms; in the Bay of Mexico, Count Pourtales' dredgings ; off Bahia 

 Honda, 418 fathoms (Jeffr.). 



Dr Gwyn Jeffreys has described the ribs as " sharp (not rounded)." They rather seem to be 

 sharply cut; but they are rounded on the top. L. 2 - l in. B. at mouth, 0'22, at apex 0036. 



The young specimen from Station 78 has at the apex on the convex curve a slit 0T in. long, 

 but interrupted by two bridges of the shell which have not been removed when the fissure was made 

 (PI. II. fig. 1). 



From Station 73 and Station 78 the specimens belong to the typical form ; that from Station 

 II., a remarkably large and fine specimen, belongs to a variety, Dentaliwrn capillosicm, var. imucicos- 

 tatum, Wats., with only about 40 instead of 65 longitudinal riblets or threads, which are very flat 

 on their top, and are divided by furrows remarkably broad and square in form. These differences 

 strike one very strongly at first ; but the transverse sculpture is identical, and there are spots on the 

 typical specimens which present an exactly similar form of ribbing. 



From Station 24 the specimen is only a fragment, and that of a young shell of very difficult 

 determination. Count Pourtales, however, having already found this species in the Gulf of Mexico, 

 his authority relieves me from the responsibility of giving the West Atlantic as a locality for the 

 species ; so I content myself with adding a mark of interrogation to the " Challenger " specimen. 



2. Dentalium cegeum, 1 Watson (PI. I. fig. 2). 



Dentalium cegeum, Watson, Prelim. Report, pt. 2, Journ. Linn. Soc. Lond., vol. xiv. p. 509. 



Station 149g. January 29, 1874. Lat. 48° 50' S., long. 69° 18' E. Off London 

 River, Kerguelen Island. 110 fathoms. Volcanic mud. 



Shell. — Long, conical, finely tapering, much and very equally bent, though less, of 

 course, as the shell grows larger, thin, pure white, porcellanous, a little chalky towards 

 the mouth, but higher up brilliant. Sculpture : Longitudinal ridges 30 to 35, unequal, 

 rounded, above close, rather high, narrow, and parted by furrows which equal the ribs, 

 but lower down these ribs become broader and flatter and the furrows widen, till towards 

 the mouth the surface becomes uniform, and the ridges are only indicated by the faint 

 strise of the furrows. Under a lens the whole surface shows a faint longitudinally 

 striated texture. On the upper part of the shell the strias of growth are verj' faint; but 

 they become rather strongly marked towards the mouth. Towards the apex the outer 

 layers for half an inch are stripped off, and leave exposed the brilliant smooth core, 

 presenting many longitudinal facets corresponding with the ridges of the outer layer. 

 There is an irregular sliort fissure with broken edges at the apex on the convex curve. 

 L. 25 in. B. at mouth 0'3, at apex 0'33. 



Than Dentalium capillosum, Jeffr., this is more conical, more curved, the ridges are fewer, and 

 the furrows between much wider and more open. 



1 a'iy=.tr, goatish. 



