DESCRIPTION OF SPECIES 45 



New Zealand, than to any other species. The principle characters serving to distinguish these species 

 are shown in Table 10. 

 Distribution. North end of North Island, New Zealand. 



The genera Synoicum Phipps, Aplidiopsis Lahille, and Polyclinum Savigny differ from Aplidium in 

 having the stomach without longitudinal folds. Their main distinguishing characters are shown in 

 Table 11. 



Aplidiopsis is intermediate between Synoicum and Polyclinum, but is apparently closer to Synoicum 

 from which it differs only in having a constriction at the junction of abdomen and post-abdomen. 

 It may be doubted whether this is a character of generic value but I retain Aplidiopsis because 

 A. discoveryi sp.n. (see p. 51) confirms the generic characters. 



Table n 



Post-abdomen 

 Not narrowed to form a 



pedicel joining abdomen 

 Narrowed to form a pedicel 



joining abdomen 

 Narrowed to form a pedicel 



joining abdomen 



Gonads 

 Testis compact, sometimes 



partially surrounding ovary 

 Testis compact partially 



surrounding ovary 

 Testis compact partially 



surrounding ovary 



Genus Synoicum Phipps, 1774 

 Synoicum adareanum (Herdman) (Text-fig. 7E; PI. I, fig. 6) 



Polyclinum adareanum Herdman, 1902, p. 195, pi. 22, figs. 1-9. 

 For synonymy see van Name 1945, p. 59. 



Occurrence. St. 175: S. Shetlands, 200 m. St. 1660: Ross Sea, 351 m. St. WS 33: S. Georgia, 

 130 m. St. MS 71 : S. Georgia, 110-60 m. 



Colony. The numerous colonies from St. 1660, in the Ross Sea, are very typical of this species. 

 There is a stalk of variable length with diameter always less than that of the head, but sometimes only 

 slightly less. The stalk is brown, tough, and transversely wrinkled. The head is ovate or roughly 

 conical, smoother than the stalk, grey or pale pink-grey. Systems of zooids are circular and not very 

 large. Kott's (1954) statement that the systems in her specimens were from 20 to 80 mm. in diameter 

 is difficult to understand, as the diameter of the whole head rarely exceeds 100 mm. Sluiter (1906) 

 records a specimen 180 mm. long and 120 mm. in diameter. A large specimen in the 'Discovery' 

 material has the head 70 mm. long and the stalk 30 mm., and another specimen has a total length of 

 130 mm. This material is therefore among the largest yet recorded. The colonies may be single, but 

 often two stalks arise from a common base. There is an error (possibly typographical) in van Name's 

 statement that Sluiter's (1906) illustration was of a specimen 10 cm. high and 65 cm. in diameter; 

 the diameter should have been 6-5 cm. 



Several small colonies from South Georgia, which I place in this species, also have a short stalk and 

 rounded head with distinct circular systems of zooids. The largest of these colonies is 18 mm. high. 



ZooiD. The zooids may attain 12 mm. in length, of which the thorax and abdomen commonly 

 occupy about 4 mm. 



Thorax. The number of oral tentacles in several zooids examined varied between sixteen and 

 twenty-four, a number considerably greater than that given by van Name (1945) who recorded about 

 twelve. All zooids examined had eighteen to twenty rows of stigmata, each row with thirty, or a few 

 more, stigmata. Van Name (1945) states that there are 'a dozen or more' stigmata in a row but Kott 

 (1954) found twenty to thirty. 



