DESCRIPTION OF SPECIES 79 



D. colligans must be considered rather scarce or at least hard to find, and it may prove to have a 

 wider distribution in the Antarctic than at present appears. 



Distribution. Antarctic (South Georgia; South Orkney Islands; Bransfield Strait). 



Distaplia cylindrica (Lesson) (PI. Ill, fig. 4) 



Holozoa cylindrica Lesson, 1830, p. 439. 

 For synonymy see van Name (1945), p. 143. 



Occurrence. St. 39: S. Georgia, 179-235 m. St. 45: S. Georgia, 238-270 m. St. 123: S. Georgia, 

 230-250 m. St. 140: S. Georgia, 122-136 m. St. 142: S. Georgia, 88-273 m - St. 148: S. Georgia, 

 132-148 m. St. 149: S. Georgia, 200-234 m. St. 189: Palmer Archipelago, o m. St. 366: S. Sand- 

 wich Islands, 155-322 m. St. 1900: Patagonian Shelf, 0-5 m. St. 1906: Patagonian Shelf, 0-5 m. 

 St. WS33: S. Georgia, 0-5 m. St. WS90: Patagonian Shelf, 82-81 m. St. WS765: Patagonian 

 Shelf, 113-119 m. St. WS 787: Patagonian Shelf, 106-110 m. St. MS 68: S. Georgia, 220-247 m. 

 B.G.L.E., Stella Creek. B.G.L.E., Port Lockroy, 0-5 m. 



Colony. Many of the specimens in the collection are only parts of colonies, but there are also a 

 few intact specimens, in which the base is attached, generally to a few small stones or pebbles. This 

 basal area is sometimes wider than the rest of the colony, and in other cases the colony widens towards 

 the base but narrows again at the immediate area of attachment. The largest colony (St. 148), measures, 

 in the preserved state, 460 cm., but a label with the specimen showed that an earlier measurement, 

 probably in the fresh state, was 485 cm. Even this colony was not intact. Another specimen was part 

 of a 'strip floating on the surface', 20-25 ft. long. This floating fragment, over 7 m. in length, repre- 

 sents one of the longest specimens ever recorded. 



In alcohol the colony is usually a dull greyish green, but the collector of the large floating strip has 

 given the following description of the fresh colony: 'general colour pale yellow white; details of 

 colour: background pale indeterminate, zooids bright creamy white'. 



Zoom. Arnback (1949, 1950) has shown that, contrary to the belief of previous workers, the zooids 

 are hermaphrodite, with the testis maturing before the ovary. The material on which she worked was 

 part of the 'Discovery' collection (St. 149), which I have been able to re-examine. This and other 

 specimens show that the zooid in the fully developed female condition has two large eggs. Two 

 embryos, or occasionally three, are found in the brood pouch. 



Biology, (a) Breeding. The breeding condition of all colonies in the ' Discovery ' collection is shown 

 in Table 24. The zooids are classed as ' well developed male ', in which the testis is moderate or large ; 

 'well developed female', with moderate or large eggs in the ovary; and 'with embryos', in which the 

 brood pouch contains one, two, or three developing embryos. No colonies were collected in the 

 winter months of May to September, but enough material was taken during the rest of the year to 

 show that zooids were already well advanced as males in October and that the testis was present from 

 then on until January when it began to regress. In October and November the ovary had not yet 

 started to develop, in December and January it was large, and thereafter decreased. The presence of 

 eggs or embryos in the samples of December, March and April indicates a breeding season confined 

 to the southern summer. No fully developed larvae were seen in any of the zooids during that period, 

 perhaps owing to a long period of incubation. If this is so larval settlement is not likely to take place 

 before April. 



Zooids in different parts of a colony are in different sexual conditions. One large colony of 130 cm. 

 illustrates this (St. 366). Zooids are absent from the basal 6 cm. of the colony. Zooids at 10 cm. from 

 the base have no gonads, no brood pouch, and no embryos. Some zooids at 20 cm. from the base have 

 an ovary and others have not, and some zooids have a spherical brood pouch, but without embryos. 



