2 g DISCOVERY REPORTS 



Biology. Table 2 suggests that in its Antarctic range this species has larger colonies, larger zooids 

 with a better developed branchial sac, and larger and more numerous larvae. The inference is that the 

 centre of distribution is in the Antarctic rather than the Subantarctic. 



Examination of many specimens showed that all the zooids of a colony keep in phase in their sexual 

 cycle, but that different colonies taken from the same station at the same time differ widely in their 

 sexual state. Thus colonies collected from St. WS 856, on 23 March 1932 varied sexually, as follows: 



No. of colonies 



No gonads present 8 



Zooids in male phase 3 



Zooids in female phase 3 



Zooids with embryos 1 



The occasional occurrence, in other samples, of zooids with both ovary and testis shows that the 

 sexes are not separate ; it is likely that the species is protandrous, as usual in Aplidium. The comparative 

 rarity of such zooids, however, suggests that the regression of the testis is rapid after the zooid has 

 functioned as a male. The relatively large number of colonies with zoiods lacking gonads and the 

 absence of gonads in zooids carrying embryos further indicates that the ovary also regresses rapidly 

 after functioning. 



Embryos or larvae were present only in colonies collected as follows : 



South Georgia Falkland Islands 



As the species did not occur in collections made in other months, however, no more can be said than 

 that breeding takes place in the southern summer, with an indication of an earlier start in the Sub- 

 antarctic than in the Antarctic region. 



Remarks. This is a species which shows slight anatomical differences in different parts of its range. 

 A variety described by Peres (1952) from Kerguelen (var. kerguelenense), has each of the oral lobes 

 bifid, and a very wide atrial languet. The differences which I have noted above between the sub- 

 antarctic and the antarctic specimens in the ' Discovery ' collections do not seem to merit systematic 

 distinction. 



Distribution. New Zealand; Chatham Islands; Subantarctic (Kerguelen, Patagonian Shelf), 

 Antarctic (Graham Land, S. Georgia). 



Aplidium fuegiense Cunningham (Text-fig. 2 A; PI. I, fig. 2) 



Aplidium fuegiense Cunningham, 1871, p. 66. 

 For synonymy see van Name, 1945, p. 43. 



Occurrence. ?St. 27: S. Georgia, no m. St. 51: Falkland Islands, 105-115 m. St. 652: Burdwood 

 Bank, 171-169 m. St. WS 71 : Falkland Islands, 82-80 m. St. WS 73 : Falkland Islands, 121-130 m. 

 St. WS76: Patagonian Shelf, 207-205 m. St. WS79: Patagonian Shelf, 132-131 m. St. WS80: 

 Patagonian Shelf, 152-156 m. St. WS 83, Falkland Islands, 137-129 m. St. WS84: Falkland 

 Islands, 75-74 m. St. WS85: Falkland Islands, 79 m. St. WS 86: Patagonian Shelf, 151-1471™. 

 St. WS90: Patagonian Shelf, 82-81 m. St. WS 91 : Patagonian Shelf, 191-205 m. St. WS92: 

 Patagonian Shelf, 145-143 m. St. WS93: Falkland Islands, 133-130 m. St. WS 94: Patagonian 

 Shelf, 1 10-126 m. St. WS95: Patagonian Shelf, 109-108 m. St. WS108: Falkland Islands, 118- 

 120 m. St. WS219: Patagonian Shelf, n6-ii4m. St. WS220: Patagonian Shelf, 108-104 m. 

 St. WS233: Falkland Islands, 185-175 m. St. WS247: Patagonian Shelf, 172 m. St. WS249: 



