196 So2ithern Cross. 



12 X 9 X 5 cm. Some of the colonies (PI. XXII., figs. 1 and 2) are 

 rather like turnips in appearance, others longer and more cylin- 

 drical, like large sausages. The ascidiozooids are large, measuring 

 over 1 cm. in length, and up to 1 • 5 mm. in breadth (dorso-ventrally). 

 In some the wrinkling of the surface layer of test at the posterior 

 end is very close (fig. 6), and in some the darkening of the surface 

 with sand grains is more marked than in others. The minute black 

 sand grains may even adhere to the test over the upper end, where 

 they are placed around the apertures of the ascidiozooids in such 

 a way as to mark out the systems with dots (fig. 4). The systems 

 are about 1 cm. in diameter, and the common cloaca measures 

 1 • 5 mm. across. Figure 5 shows the test covering a system as 

 seen from the underside when sliced off. 



This species comes near Polydinum giganteum and P. globosum, 

 found at Port Jackson, Australia. 



Psammaplidiura nigrum. (Plate XXIII., figs. 1-3.) 



External appearance. — The colony is large, flat, and soft, 

 measuring 10 x 6 X 1 cm., nearly black in colour, and finely sandy 

 all over. It is marked with conspicuous coarse granulations, which 

 indicate the anterior ends of the ascidiozooids, and is also marked 

 out into polygonal areas by slight creases (see PI. XIIL, fig. 1). 



The Test is very soft and flimsy, easily torn, and giving no stiff- 

 ness to the colony. It is of a dark grey colour even when free of 

 sand. Most of the sand is in the surface layer, but there is a little 

 throughout. The sand grains are dark, which adds to the black 

 appearance of the colony. 



The Branchial sac has at least a dozen rows of numerous small 

 stigmata (fig. 3). 



Tlie Mantle is muscular. There is a rather large muscular 

 branchial siphon, and a large atrial languet. 



Locality. — " Cape Adare, 26 fathoms, 14th November, 1899." 



In addition to the colony described above there is a second, 

 measuring 4x3x1 cm. (see fig. 2). Both colonies are remark- 

 ably soft and flabby. This and the black colour are characteristic 

 features of the species. 



Psammaplidium antareticum. (Plate XXIIL, figs. 4-6.) 



External appearance. — Colony irregular in form, or rising into a 

 convex mass in centre, quite firm with a thick layer of black sand 

 over the surface. Size of one colony 8x6x4 cm. 



