LITUOLIDAE loi 



a narrow slit, extending down the inner edge of the apertural face of final chamber. 

 Colour dark grey, owing to the incorporation of black volcanic sand. Wall constructed 

 of fine sand grains and cement, smooth but unpolished. 



Diameter up to 075 mm. ; thickness about 0-25 mm. 



This large and striking form is not uncommon in 329 m. off Zavodovski Island in the 

 South Sandwich group, but did not occur at any other station. Its dark colour is a 

 feature common to all the Arenacea at this station, and elsewhere it might be expected 

 to have the yellow-orange colour characteristic of the genus. It is probably closely 

 related to T. nitida, with which it agrees in its depressed umbilicus, but difl^ers in having 

 only six chambers instead of nine to the convolution, a lobulate peripheral edge and 

 coarser construction. In the latter respect it resembles T. nana, which has not a depressed 

 umbilical area. 



195. Trochammina nitida, Brady (SG 138). 

 One station: 365. 



The species is curiously rare in the material, being represented by a single specimen 

 which is not typical, having only seven chambers in the final convolution. It appears to 

 be almost entirely composed of cement. 



196. Trochammina bradyi, Robertson (F iii) (SG 137). 



Sixty-five stations: 169, 170, 171, 177, 180, 181, 186, 190-2, 194-8, 203, 204, 206, 360, 362, 369, 

 382; 62° 57' S, 60° 20' 30" W; WS 199, 203, 377, 383-7, 389, 391, 393, 395, 396, 471, 472, 474, 

 479, 480, 482-90, 493, 494A, 494B, 496, 502, 503, 509-12, 514, 515, 552, 553, 555. 



Generally distributed and at all depths down to 5029 m., but not recorded at any of 

 the stations outside the Antarctic convergence line. 



It is very common at Sts. 171, 177, 181, 198, WS 383, 384, 385, 386, 479 and 483; 

 of varying frequency at the remaining stations, and sometimes represented by only one 

 or two specimens. Its wide distribution and frequency all over the Antarctic area is the 

 more noticeable because of its extreme rarity in the Falklands and South Georgia, where 

 it might have been expected to occur in similar abundance, as it is met with frequently 

 in British dredgings and is therefore not essentially a cold-water species. 



There is great variation in the size of specimens at different stations, also in the colour, 

 which varies from yellowish white through all shades of yellow and orange to dark 

 brown. The number of chambers visible is typically five, but at the deep-water stations 

 WS 552, 553 and 555 specimens showing only four chambers of approximately equal 

 size occur. They bear some resemblance to the compressed form of Pullenia sphaeroides 

 which is occasionally found, also to Haplophragtnoides quadra tus (No. 164). At many 

 stations specimens occur with the number of visible chambers exceeding five, and 

 arranged in an irregular fashion. 



197. Trochammina globigeriniformis (Parker and Jones) (F no a) (SG 140). 

 Forty-eight stations : 163, 167, 171, 177, 181, 192, 194, 195, 198,202,203,360,362,365,369,383, 



385; 62° 57' S, 60° 20' 30" W; WS 201, 205, 377, 384, 385, 391, 393, 395, 400, 403, 468, 469, 472, 

 474,479, 483, 484, 487, 497, 503, 506, 507 B, 511-15. 517. 553. 555- 



