18 W. A. HERDMAN. 



thorax is, however, so contracted that it is almost impossible to make out the internal 

 characters. Any attempt to stretch out the contracted tissues leads to their disinte- 

 gration. A much corrugated endostyle, a large number of small stigmata, and a few 

 short, simple, branchial tentacles were all that could be made out. 



This is the first member of the family Clavellinidse found in Antarctic Seas. 



DIDEMNID.E. 



LEPTOCLINUM GLACIALE. 

 (Plate VI., figs. 1-4.) 



The single specimen is a large but thin colony expanded over the surface of a 

 fragment of dark-coloured rock (Plate VL, fig. 1), obtained from " Dredge off Coulman 

 Island 13. i. 02 100 fathoms." It measures 3' 5 x 4' 5 cm. and from 1-3 mm. in 

 thickness. It is of a grey colour, but that is largely due to its thinness, which allows 

 the dark stone below to show through. The surface is smooth and glistening, and is 

 marked with oval spots which indicate the bodies of the rather large flattened ascidio- 

 zooids. Part of the surface is torn, and the figure (Plate VI. , fig. 1) is from a 

 photograph which represents the greater part of the colony nearly twice the natural size. 

 The arrangement of the ascidiozooids seems quite irregular, and no common cloacal 

 apertures are visible. In the ov'ate areas over the ascidiozooids the calcareous spicules 

 are less numerous (fig. 4), and therefore the colony is less opaque and less white at 

 these points. Around the branchial apertures of the ascidiozooid there is a still 

 clearer rounded area (fig. 4), towards one end of which the six-lobed opening is seen. 



The calcareous spicules have very numerous and unusually fine rays (fig. 3). In 

 some cases they are more irregular and blunter, but many of them have fine needle-like 

 points. In addition to the spicules there are many large, rounded, triangular, or 

 stellate coarsely granular cells (fig. 2), scattered through the test. 



The two or three ascidiozooids examined, on the edge of the torn part, did not 

 seem to be in sufficiently good condition to give any information as to the structure, 

 and it did not seem justifiable to spoil the appearance of the single colony by tearing 

 it further. 



LEPTOCLINUM sp. 



A small package of specimens, belonging to the ' Discovery ' collection, which 

 reached me after the plates were printed, and when this report was nearly finished, 

 included five small rounded colonies of a Leptoclinum, measuring from 1 to 1 5 cm. in 

 length, obtained from "Winter Quarters, 3. vi. 03., 10 hole, 130 fathoms," and 

 all of them attached to fragments of the calcareous polyzoon Cellaria sp. There is 

 also one still smaller similar specimen from "Winter Quarters, 4. ix. 03, 12 hole, 

 D. net." 



