TUNIC ATA. 17 



and evidently variable forms in the one species, or (2) to describe each group of 

 individuals separately, and so recognise several species differing but slightly from one 

 another. In the present state of knowledge all accurate descriptions of groups of 

 individuals have their value, but it is unnecessary here to regard them as distinct 

 species, and I prefer to take that course in the present instance. 



In external appearance the 'Discovery' specimens (PI. III., figs. 1-3) agree 

 closely with von Drasche's figure of C. norarse, do not differ from Traustedt's 

 description of C. i>uin>/<>t</, and are like in shape, but much smaller than, the specimen 

 figured in the 'Charcot' report; but it is evident from Dr. Sluiter's description that 

 he had also smaller individuals under examination, and we arc accustomed in the 

 Tuuicata to individuals in various species attaining relatively gigantic dimensions. 



The characters of the branchial sac, dorsal languets, and tentacles of the 

 ' Discovery' specimens are sufficiently shown in our figures (Plate III., figs. 1-6). The 

 dorsal tubercle we have figured (fig. G) is intermediate in character between the two 

 conditions figured by Dr. Sluiter for C. antarctica ('Charcot' report, pi. ii., figs. 

 29 and 30). The lower part of the tubercle in Sluiter's fig. 29 is probably abnormal 

 in character. 



The alimentary canal and gonacls agree very closely in our specimens with the 

 condition figured in the report on the 'Charcot' Expedition. On the whole, I think 

 that the differences in detail between our specimens and the description of Corella 

 ntititrctica may be accounted for by the difference in size and presumably in age. 



This species seems to be widely spread in the southern hemisphere. In addition 

 to the coasts of Brazil and Chili (Traustedt) and the Indian Ocean (v. Drasche), it has 

 been recorded from the Cape of Good Hope (Sluiter) and Patagonia (Michaelsen), and 

 finally from the Antarctic (' Charcot' and ' Discovery' expeditious). 



CLAVELLINID^E. 



STEREOCLAVELLA ANTARCTICA. 

 (Plate VI., figs. 5-7.) 



There are two colonies (Plate VI., figs. 5 and G), obtained from Winter Quarters, 

 in McMurdo Bay, 8. ix. 03., which may be placed in this genus. 



The larger (fig. 5), measuring 3 cm. across the base, and about the same in height, 

 contains eight or ten individuals, and the smaller (fig. 6), some four or five. In both 

 cases the test is irregularly lobed, the basal mass being more solid and the distal part 

 cut up into roughly cylindrical projections one corresponding to each ascidiozooid. 



The ascidiozooid has a small clear thorax and a large opaque abdomen the 

 alimentary canal being apparently distended with dark muddy food. The apertures are 

 not distinctly lobed (fig. 7), the atrial being somewhat square in outline. The whole 







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