94 DISCOVERY REPORTS 



confined to the deeper stations, between 1500 m. at St. WS 505 and 5029 m. at St. 

 WS 553. The best specimens were found at St. 362 in the Scotia Sea, depth 3370 m. 

 At this station and several others the type species was not recorded, but too much im- 

 portance should not be attributed to this having regard to the small samples of material 

 available for examination. The records are spread over a wide area in the Weddell, 

 Scotia and Bellingshausen Seas. 



Length up to o-6o mm. or more; breadth 0-40 mm. ; thickness about 0-15 mm. 



Genus Ammomarginulina, Wiesner, 1931 



176. Ammomarginulina ensis, Wiesner (SG 122). 



Twenty-one stations: 360, 382-6; WS 199, 203-5, 400, 403, 468, 471, 472, 474, 495, 502, 503, 

 516,517- 



Generally distributed over the entire area, but confined to deep water between 2582 

 and 4773 m. It is one of the most characteristic Antarctic species and often occurs in 

 considerable numbers, notably at Sts. WS 502 and 503 in the far south-west of the 

 Bellingshausen Sea, where it is common in over 4000 m. It occurs frequently also at 

 Sts. 382, 383, WS 471 and 472 which are in the Scotia Sea to the north of the South 

 Shetlands. There is considerable range of variation, tw^o forms occurring often in com- 

 pany, one being broad and flat and microspheric ; the other, narrow and with the ex- 

 tended portion almost cyhndrical, is the microspheric form. The axis of growth is often 

 more or less curved, so that the extended chambers are not in the same plane as the 

 early spiral portion of the test. 



Genus Placopsilina, d'Orbigny, 1850 



177. Placopsilina confusa, Cushman (F 98) (SG 123). 



Placopsilina cenomana, Brady {pars), 1884, FC, pi. xxxvi, figs. 2 and 3 (only). 

 Placopsilina co?ifusa, Cushman, 1918, etc., FAO, 1920, p. 71, pi. xiv, fig. 6. 

 Placopsilina cetiomana, Heron-Allen and Earland, 1932, F, p. 341, pi. vii, fig. 25. 

 Placopsilina cenomana, Earland, 1933, SG, p. 83. 



Six stations: 384; WS 468, 469, 494 A, 495, 505. 



A few specimens only were recorded, but the species is probably fairly common when 

 suitable material for attachment is available. 



Since the Falkland and South Georgia reports were published Dr J. A. Cushman has 

 been good enough to send me a specimen of his species P. confusa. It is unquestionably 

 identical with the organism recorded in those reports, and with British specimens 

 hitherto known as P. cenomana. Cushman regards it as distinct from the larger tropical 

 organism. Except for its smaller size and propensity for deeper water, the size in my 

 opinion being influenced by the depth, it appears to have no structural differences, and 

 I doubt its zoological distinction. It is, however, sufficiently characteristic for separa- 

 tion taxonomically. 



The "distinctive organism" referred to in the Falkland report is quite difl^erent, and 

 is described in this report under the new generic name Placopsilinella (see No. 178). 



