121 



DESCRIPTION OF SPECIES 



epidermis they are to be regarded as specially developed test vessels. Great numbers of blood cells, 

 many of them phagocytes, lie in the test matrix. The function of the atrial organs is still unknown. 



Parietal organs. Michaelsen (1900) noted the existence of other enigmatic structures which have 

 become known as the parietal organs. These were described as a pair of swellings of the body wall, 

 one on each side, and containing vacuolated cells. I have examined many specimens of P. legumen 

 without finding parietal organs, although they are easily seen in related species (see p. 122), and I can 

 only conclude that they are not always present or recognizable in P. legumen. 



Branchial sac. In a specimen with body 3-9 cm. and stalk 3-2 cm. the branchial sac has the 

 following arrangement of longitudinal bars: dorsal line 2 (22) 2 (13) 3 (20) 3 (20) 3 (15) 4 (12) 1 (3) 1 

 endostyle. 



Biology. There are not enough specimens to indicate the breeding season of this species. 



s 



54 



4 

 3 



2 



I 



5 6 



TOTAL LENGTH CM 



Text-fig. 48. Pyura legumen (Lesson). Relation between the ratio body-length/stalk-length and the total length. 



In some animals the intestine is filled with plankton organisms, mainly small algal cells and 

 Globigerina sp. together with diatoms. 



Remarks. I discuss this and the two related species P. georgiana and P. bouvetensis on p. 124. 

 Distribution. Subantarctic (Falkland Islands, Patagonian Shelf, Magellen region). 



Pyura georgiana (Michelsen) (Text-figs. 47D-F; 49; 50; PI. IV, fig. 7) 

 Boltenia georgiana Michaelsen, 1898, p. 364. 



Occurrence. St. 39: S. Georgia, 179-235 m. St. 42: S. Georgia, 120-204 m> St. 123: S. Georgia, 

 230-250 m. St. 140: S. Georgia, 122-136 m. St. 144: S. Georgia, 155-178 m. St. 145: S. Georgia, 

 26-35 m - St. 148: S. Georgia, 132-148 m. St. 152: S. Georgia, 245 m. St. 156: S. Georgia, 200- 

 236 m. St. WS 62: S. Georgia, 26-83 m - St - ws 5 6 7 : s - Georgia, 145 m. St. MS 14: S. Georgia, 

 190-110 m. St. MS 68: S. Georgia, 220-247 m. 



External appearance (Text-fig. 47 D ; PI. IV, fig. 7). This species differs from P. legumen in having 

 the stalk originating from near the middle, or somewhat towards the anterior end, of the ventral side, 

 instead of at the extreme anterior end of that side, and passing down ventrally from the body and not 



16 DM 



