LITUOLIDAE 9S 



Genus Placopsilinella, gen.n. 

 Test minute, sessile, chitinous with some admixture of ferruginous cement, consisting 

 of an indeterminate number (up to 50 or more) of subglobular chambers in a single 

 layer. Initial chambers apparently arranged in a loose spiral line of single chambers, 

 subsequently developing into an irregularly curving line with at first two, then three or 

 four chambers abreast. No external aperture or means of communication between the 

 chambers can be traced. Colour deep orange-yellow. 



178. Placopsilinella aurantiaca, sp.n. (Plate III, fig. 18). 

 Eight stations: 360, 384; WS 204, 403, 468, 469, 494A, 517. 

 Very rare at all stations. 



The characters of the genus are a sufficient description of the genotype species, which 

 is of rare occurrence and apparently confined to deep water. The stations are in the 

 Scotia and Bellingshausen Seas, the Drake and Bransfield Straits, and the depths are 

 between 2770 and 4344 m., except one station, WS 494A, which is in the comparatively 

 shallow depth of 1035 m. This species is generally adherent to other Foraminifera, 

 usually Globigerina or Globorotalia, and is then conspicuous by the bright orange colour 

 of the chambers contrasting with the white test of its host. The chambers look like rows 

 of tiny oranges. But it also occurs on sand grains or pebbles at Sts. 360, WS 468, 469 

 and 494 A, and at St. 384 two small manganese nodules bore several colonies. 



The initial spiral which is most evident in the specimen from St. WS 204 seems to 

 mark an affinity with Placopsilina, from which it differs in the development of double 

 or triple rows of chambers. I have not seen any case in which chambers have been 

 superimposed. 



Diameter of separate chambers up to 0-03 mm. 



A colony may have a length up to 0-3 mm. and breadth 0-2 mm. 



This interesting little form probably has a wide distribution in cold water, as I have 

 specimens from the North Atlantic in 1782 fathoms (U.S.F.S. 'Albatross', St. 2569, 

 39° 26' N, 68° 03' W). The species is of more frequent occurrence than in the Antarctic, 

 but the individual chambers are darker and more chitinous, perhaps rather smaller. 

 I have also found a specimen at Challenger St. 5 (24° 20' N, 24° 28' W, 2740 fathoms). 



Sub-family TROCHAMMININAE 

 Genus Ammolagena, Eimer and Fickert, 1899 



179. Ammolagena clavata (Jones and Parker) (F 99) (SG 124). 



Fifteen stations: 373, 383, 385, 387; WS 201, 203, 204, 468, 469, 471, 495, 502, 507 A, 517, 555. 



Generally distributed but never common, although this may be due largely to the 

 absence at many stations of mineral fragments suitable for a sessile organism. At several 

 stations the only specimens were sessile on other Foraminifera. It was frequent at 

 St. WS 555, where a very large specimen was found attached to Cyclammina cancellata, 

 and many very small specimens on sand grains. Frequent also at St. 383, rare or very 

 rare at the remaining stations. Ferruginous specimens are infrequent, the usual colour 



