lyS DISCOVERY REPORTS 



a number of minute tubercles, which presumably support spines in the living animal. 

 Colour white, rather glassy. 



Maximum breadth of final convolution about o-6o mm.; height measured from apex 

 to lowest point of final chamber about 0-50 mm. 



This rather striking species occurs at four stations only , all in the deep water of the Drake 

 Strait and Scotia Sea, 3328-3959 m. Two of the stations, 385 and WS 469, are just on 

 the Antarctic convergence line, and the others within it. It is very rare, three specimens 

 at Sts. WS 204, 403, one at St. WS 469, and seven at St. 385. From the large size of the 

 aperture and the thinness of the shell it is almost certainly a pelagic species, and probably 

 of South Pacific habitat. Its affinities appear to be with G. dutertrei, d'Orbigny, from 

 which it differs in its greater size, the greater height of its spire, its much larger aperture, 

 and a lesser number of chambers. 



The outline figure drawn by Fornasini (F 1898, GFI, p. 209, fig. 4) from d'Orbigny's 

 " Planche inedite " of G. helicina is very suggestive of G. megastoma, but cannot represent 

 the same species. See note on the type of G. helicina in the Falklands report, p. 401 . 



464. Globigerina pachyderma (Ehrenberg) (F 310) (SG 281). 



Eighty-four stations: 162, 167, 170, 175, 177, 180, 181, 182, 186, 187, 190, 192, 194-6, 200, 202, 

 203, 360, 362, 363, 366, 369, 382-7; 62° 57' S, 60° 20' 30" W; 64° 56' S, 64° 43' W; Port Lockroy; 

 WS 202-5, 382-5. 389. 391-3. 395. 396. 403. 468. 469. 471. 472. 474-6. 479, 480, 482, 483, 485-8, 

 493. 494A, 495-8, 502, 505, 506, 507 A, 507B, 509-17, 553, (555 fossils). 



Almost universally distributed and irrespective of depth, the records ranging from 

 93 to 4773 m. It is the dominant form at Sts. 384, 385, 386, WS 205, 403 and 507B, all 

 of which except the last are in deep water. It is also very common at Sts. 170, 175, 180, 

 369, 383, 387, WS 204, 468, 469, 472, 482, 498, 505, 511, 512 and 517, and although 

 many of these stations are in deep water others are shallow, as St. WS 482, loo-o m. 

 Depth therefore does not appear to affect its distribution or numbers very greatly. At 

 many of the stations it is extremely rare, though common under similar conditions at 

 another station not far away. There is great variation in size and in the nature of the 

 aperture, and at many stations it is possible to obtain a series of specimens showing the 

 transition from thin-shelled and hyaline forms with large arched apertures, to the thick- 

 shelled nearly globular forms, in which the chambers are almost unrecognizable and the 

 aperture is reduced to a central hole. Fossil specimens were not infrequent at St. 

 WS555. 



Genus Orbulina, d'Orbigny, 1826 



465. Orbulina universa, d'Orbigny (F 314) (SG 285). 

 One station : WS 403. 



A few dead shells, possibly current-borne, at St. WS 403 in the Drake Strait. 



Genus Hastigerina, Wyville Thomson, 1876 



466. Hastigerina pelagica (d'Orbigny). 



Nonionina pelagica, d'Orbigny, 1839, FAM, p. 27, pi. iii, figs. 13, 14 on plate; figs, i, 2 in text 

 incorrect. 



