ASTRORHIZIDAE 63 



Genus Webbinella, Rhumbler, 1903 



65. Webbinella depressa, Heron-Allen and Earland (F 64). 

 Two stations: 27, 145. 



A single specimen only at St. 27 and two excellent specimens at St. 145. 



66. Webbinella limosa, sp.n. (Plate II, figs, i, 2). 

 Two stations: 27, 126. 



Test sessile, monothalamous, irregular in form but usually roughly circular, more or 

 less highly convex. Wall rather thick and without visible aperture, composed of mud 

 and very fine sand grains. Friable but sufficiently firm to allow the convex test to be 

 detached as a whole from its surface of attachment. The test is then seen to consist of a 

 single irregularly shaped cavity with thin basal floor. The cavity is nearly always filled 

 with a mass of Diatoms and mud ingested as food. Colour yellowish grey. 



Size from i-o to 2-0 mm. in diameter. 



Not uncommon at the two stations where it occurs sessile on small pebbles. Most of 

 the specimens have been more or less damaged in the cleaning process, the convex shape 

 and friable wall causing it to be easily worn away. 



W. limosa is no doubt closely allied to W. depressa, Heron- Allen and Earland, but is 

 readily distinguishable owing to its greater convexity, thicker but more friable wall and 

 yellowish colour. 



Genus Tholosina, Rhumbler, 1895 



67. Tholosina bulla (Brady) (F 65). 



Seventeen stations: 27, 45, 123, 140, 144, 145, 148, 149; WS 27, 33, 40, 42, 154, 334, 31^3; 

 MS 14, 68. 



Less abundant than T. vesiciilaris but common at Sts. 27, 144 and 149 and very 

 common at WS 33. Mostly rare elsewhere. There is considerable range of variation in 

 the convexity of the test: very highly convex specimens at St. 149 and MS 68. At Sts. 

 45 and 123 small specimens attached to sponge spicules and zoophyte stems are almost 

 globular in shape. They appear to be very similar to Wiesner's figures of Tholosina 

 laevis, Rhumbler (W. 1931, FDSE, p. 86, pi. vii, figs. 80-2). If they are identical there 

 seems little excuse for the formation of a new species. 



The material employed varies at different stations, at some only fine sand is used, at 

 others coarse sand, the latter being distinguishable from T. vesiciilaris only by the 

 absence of the apertural tubes. 



68. Tholosina protea, Heron-Allen and Earland (F 66). 



Six stations: 27, 144, 145; WS 25, 27, 154. 



Detached specimens only were observed, except at St. 145. They are frequent, both 

 large and small, at the three WS stations, rare at the others. Nearly all the various 

 eccentric shapes observed in the Falkland material occur, but many of the specimens 



