ASTRORHIZIDAE 67 



76. Thurammina protea, sp.n. (Plate II, figs. 3-10). 

 Nine stations: 20, 27, 123, 140, 144, 148; WS 154, 348; MS 14. 



Test free or sessile, typically monothalamous but sometimes forming an aggregation 

 of two or more individuals, without direct communication with each other beyond the 

 apertures in the wall, which is thin but firm, constructed of fine sand and ferruginous 

 cement on a chitinous membrane. Apertures in the form of small nipple-like protu- 

 berances, very variable in number and prominence, either scattered over the wall of the 

 test or more frequently confined to salient edges. Shape protean, cushion-like or 

 hemispherical when sessile, but when free irregular, angular and polyhedral. Colour 

 rusty brown. Size very variable, ranging up to i-6 mm. in diameter. Average i-o mm. 



Although not generally distributed T. protea is one of the most striking and character- 

 istic of the South Georgian Foraminifera and by far the most abundant representative 

 of its genus, all the other species being comparatively rare. It is common at St. 27 and 

 WS 154, frequent to rare at the other stations. 



It is more frequently found in the sessile condition than any other form of Thiiram- 

 niino, and in this condition appears to be closely related to T. hemisphaerica, Haeusler 

 (H. 1883, ALB, p. 60, pi. iv, figs. 14, 14 (?; and H. 1890, FST, p. 47, pi. vii, figs. 10, 11). 

 Young specimens in the sessile condition are circular and cushion-shaped, almost 

 devoid of nipples, or having them only round the margin. Later the specimens become 

 irregular in outline and form, and develop nipples over the surface. 



There is no doubt that the extraordinary shapes assumed by the organism are largely 

 due to the conditions under which it lives, either attached to other bodies, or in crevices. 

 In many cases it takes up its abode inside the empty tubes oi Hyperammina stibnodosa, and 

 probably inside other tube-forming organisms. This leads to the formation of a cylin- 

 drical test, examples of which were found at St. 144 {in situ in H. stibnodosa) and WS 

 154. The specimen from the latter station is an aggregate of three individuals in line. 



The shape of the species is particularly protean at WS 154, the irregularity being 

 due to the formation of the test in the crevices of other organisms, or between pebbles. 

 The specimens have taken the exact impress of the cavity, and the apertures are confined 

 to the exposed marginal edge, the remainder of the test being quite smooth. 



At St. 27 a very curious specimen was found which had grown around two large 

 tetractinellid sponge spicules, possibly while the spicules were still projecting from the 

 sponge. Another instance of incorporated spicules was observed at WS 348, but such 

 inclusions, whether of spicules or large sand grains, are very rare. 



T. protea is evidently closely related to T. haeusler i, but appears to be quite a distinctive 

 local form. 



77. Thurammina tuberosa, Haeusler. 



Thurainmina tuberosa, Haeusler, 1890, FST, p. 49, pi. vi, fig. 24; pi. vii, figs. 6-9. 

 Thurammina popillata var. tuberosa, Heron- Allen and Earland, 1912, etc., NSG, 1917, p. 548, 

 pi. xxviii, figs. 13-16. 



Three stations: 123, 144, 148. 



