ASTRORHIZIDAE 53 



Very rare at the two stations at which it was observed, but eight specimens in all were 

 found. 



It differs from A. augulosa, Brady, in the character of the interior chamber, which is 

 large and occupies the whole body of the test, the apertures opening directly into it. In 

 Brady's species, the walls, built of fine sand only, are very thick and the central chamber 

 is not much more than a junction, formed by the three tubes diverging to the orifices at 

 the angular points. 



Genus Iridia, Heron- Allen and Earland, 19 14 



37. Iridia diaphana, Heron-Allen and Earland (F 52). 

 Two stations: 30; WS 25. 



Several very good specimens were found at WS 25, and a single, less typical, at St. 30. 



Genus Vanhoeffenella, Rhumbler, 1905 



38. Vanhoeffenella gaussi, Rhumbler (Plate I, figs. 16-21). 



Vanhoeffenella gaiissi, Rhumbler, 1905, MF, p. 105, fig. 9; 1909, FPE, p. 216, fig. 57. 

 Vanhoeffenella gaussii, Heron-Allen and Earland, 1922, TN, p. 76, pi. i, figs. 14, 15. 



Nine stations: 27, 45, 126, 140, 144, 148; WS 51, 154, 334. 



Frequent at Sts. 27, 140, 144, 148, rare or very rare elsewhere. 



Vanhoeffenella has hitherto been known only from Rhumbler 's original description ; 

 our own note on two specimens found in the Terra Nova material (exact locality 

 unknown), and recently from a record by Wiesner (W 193 1, FDSE, p. 78, pi. iii, 

 figs. 21-6) whose specimens came from the Antarctic, near the coast of Kaiser Wilhelm 

 Land, depth 70-385 m. Its occurrence, in considerable numbers, in some of the South 

 Georgian material greatly enlarges our knowledge of the genus, and enables me to correct 

 the observations made on the Terra Nova specimens. We then described "the angular 

 framework supporting the characteristic chitinous membrane which forms the two faces 

 of Vanhoeffenella" as "a hollow tube with labyrinthic interior, constructed of minute 

 Diatom and mineral debris". 



The present examination of a long series of specimens proves that this tubular 

 appearance is only assumed by collapsed and pauperate individuals, and that the struc- 

 ture is really much more simple. 



Vanhoeffenella may be compared to a tambourine, the parchment sides of which are 

 represented by the two chitinous faces. These are separated, and in life kept widely 

 apart, by the rim, which is a flat belt of chitin agglutinated with mud, fine sand and 

 Diatoms. At intervals this belt widens out and forms tubular extensions. These vary in 

 number from one or two in the smallest individuals to as many as six or seven in large 

 specimens. They are formed by the extension of one of the chitinous faces together with 

 one edge of the sandy belt. The chitin forms the greater part of one side of the tube, the 

 sandy rim folding over on itself to complete the other side, and the end. The tubes are 

 formed from either edge of the belt ; the sandy side of a tube may be either uppermost or 

 underneath, as the individual lies on one chitinous face. Most specimens show tubes 



4-2 



