GLOBIGERINIDAE i77 



mens become quite rounded owing to the thickness of the wall and diminished size of 

 the aperture, and are very similar to G. pachyderma , which is also very abundant and 

 variable at that station. 



460. Globigerina dutertrei, d'Orbigny (F 307) (SG 279). 



Forty-two stations: 164, 167, 170, 175, 177, 180, 181, 195, 196, 200, 201, 363, 366, 369, 383-7; 

 Port Lockroy; WS 204, 385, 389, 391-3, 468, 469, 481-3, 490, 493, 498, 502, 505, 506, 507 A, 507B, 

 510, 513, 517. 



Generally distributed and very common at Sts. 384-6 and WS 469. It is also common 

 at Sts. 170, WS 204 and 517 and frequent at eleven other stations, 175, 195, 201, 363, 

 WS 392, 481, 482, 505, 506, 507A and 507B. Elsewhere generally very rare. There is 

 great variation in size, also in the height of the spire and size of the aperture, all of these 

 tending to produce specimens running into G. pachyderma. 



461. Globigerina conglomerata, Schwager (F 308) (SG 280). 



Forty-six stations : 167, 170, 175, 177, 180, i8i, 186, 187, 190, 196, 199, 200, 201, 363, 366, 369, 

 384-7; 62° 57' S, 60° 20' 30" W; WS 202-5, 387, 392, 394, 395, 403, 468, 469, 472, 474, 479, 481-3, 

 485, 496, 505, 506, 507 A, 507B, 514, 517. 



Generally distributed but not abundant except at a few stations. It is very common 



at Sts. 170, 385 and 387, WS 204, 403, 468, 469, 505, 506, 507A, 507B, and at the last 



four of these stations, which are in the Bellingshausen Sea, it is the dominant species. 



At the remaining stations it varies from moderate frequency to very rare. There is great 



variation in size at different stations, and also in the nature of the aperture, which is 



sometimes very large and open, at others more or less closed by a projecting flap of the 



final chamber. From this last condition specimens pass almost imperceptibly into the 



large thin- walled type of G. pachyderma. 



462. Globigerina elevata, d'Orbigny (F 312) (SG 284). 

 Five stations: 180, 385; WS 204, 205, 393. 



Very common, except at Sts. WS 205 and 393 where it is rare. 



Wiesner (W. 193 1, FDSE, p. 133) proposes the new name G. bradyi for this small 

 form, which has been recorded from many localities under the names of various species 

 of Globigerina, G. rubra, G. elevata, G. trochoides. The suggestion seems good, as it 

 appears to be a true species and does not approach very closely to any of the foregoing 

 species. I am, however, retaining the name under which it has been recorded pre- 

 viously in this series of reports. 



463. Globigerina megastoma, sp.n. (Plate VIII, figs. 9-12). 

 Four stations: 385; WS 204, 403, 469. 



Test large and very thin-walled : a trochoid spiral of about zl convolutions, all visible 

 on the dorsal side ; the last convolution only is visible on the ventral side, which is deeply 

 recessed. The aperture, situated on the inner edge of the final chamber, is large and 

 semicircular, with a reverted lip. The chambers, which are greatly inflated, increase 

 rapidly in size, the sutures being deeply depressed ; four chambers do not quite com- 

 plete the final convolution. The surface is almost smooth, not areolated, but covered with 



DX ^3 



