TUNIC AT A. 19 



This Leptodlnum is of a gloaming white colour, and is hard and brittle, and much 

 more densely crowded with calcareous spicules than in the case of the preceding species. 

 The spicules are especially abundant in the superficial layer of the test, making it white 

 and opaque. In the deeper layer alongside the viscera of the ascidiozooids there is a 

 certain amount of yellow pigment in the test. 



These are probably young colonies ; and although they do not seem to agree in 

 character with any of the described Antarctic species of the genus, still the material 

 does not seem sufficient for a satisfactory description of a new species. I therefore 

 prefer merely to record that there is this second species of white Leptoclinum present 

 in the neighbourhood of McMurdo Bay. 



POLYCLINIM. 



AMAROUCIUM ANTARCTICUM. 

 (Plate VI., figs. 8-13.) 



A single club-shaped colony (Plate VI., fig. 8) was obtained from " Dredge off 

 Coulman Island 13. i. 02 100 fathoms." It measures 5 x 3 cm. in extreme breadth 

 at the upper swollen part of the stalk, but the upper surface of the head, where the 

 ascidiozooids are placed, measures 2 cm. in diameter. The figure is from a photograph 

 representing the colony about one-fifth larger than the natural size. The shape is not 

 unlike that of the European Amaroucium proliferum or A. argus. 



There is a little sand imbedded in the outer layers of the test (see figs. 9 and 10) : 

 not sufficient to give the surface a sandy appearance, as in the case of species of 

 Psammaplidium, but just enough to make it gritty to the knife or needle. The large 

 ascidiozooids are seen in situ in fig. 10, and fig. 11 shows one of them extricated from 

 the tough test. 



There are many rows of stigmata (fig. 11), and their arrangement and character 

 are seen from the enlarged fragment of the branchial sac (fig. 13). 



THALIACEA. 

 SALPIOE. 



There are two jars of Plankton, largely composed of Salpidae, in the collection, 

 in addition to a number of tubes containing specimens of Salpa and Oikopleura that 

 had been caught individually or picked out. Most of this Plankton material was 

 obtained in far Southern, but not strictly Antarctic seas (such as 40 to 45 S. Lat), 

 and it includes only well-known cosmopolitan forms. Still, as it is a part of the 

 ' Discovery ' Collection, these specimens and localities will be given with the rest in the 

 following list. 



VOL. V. 



