48 DISCOVERY REPORTS 



confirm this. As these colonies contain mature zooids, they are not to be regarded as young specimens. 

 Corresponding differences in the zooids are more difficult to find, but Table 12 lists the constant 

 distinctions shown by the colony and zooids of the specimens in the ' Discovery ' collections. 



Table 12 



S. adareanum S. georgianum 



Colony Stalk firm, opaque, wrinkled and sharply marked off Stalk and head not sharply marked off from each 



from head. Colony massive other; both transparent. Colony slender 



Zooid 18-20 rows of stigmata I 3 _I 5 rows of stigmata 



Anus opposite 13th row Anus opposite 7th or 8th row 



Stomach pear-shaped Stomach not pear-shaped 



Previous accounts do not always bear out these distinctions. Thus the number of rows of stigmata 

 in S. adareanum is variously given as ten to twelve (Sluiter, 1906), fifteen to twenty (Kott, 1954), 

 fourteen or fewer up to twenty (van Name, 1945), and about twenty (Herdman, 1902). The relative 

 position of the anus is not clear in previous descriptions, and the stomach has been variously described 

 but was often stated to be contracted. The most reliable distinction appears to be the form and habit 

 of the colony, and accounts of S. adareanum agree with most of the characters listed above. 



Distribution. Antarctic (South Georgia), Subantarctic (Patagonian Shelf). 



Synoicum giardi (Herdman) (Text-fig. 8 A; PI. I, fig. 8) 



Morchellium giardi Herdman, 1886, vol. 14, p. 181, pi. 25, figs. 1-3. 



Synoicum giardi Hartmeyer, 191 1, p. 550, pi. 47, fig. 7, pi. 56, figs. 1-3; Kott, 1954, p. 169, fig. 62. 



For other references see Kott, 1954, p. 169. 



Occurrence. St. WS27: S. Georgia, 107 m. St. MS 64: S. Georgia, 7-15 m. St. MS 71: 

 S. Georgia, 1 10-60 m. 



Colony (PI. I, fig. 8). One colony measures 2-7 by i-6cm. in diameter, and about 0-5 cm. in 

 thickness, and is thus rather flatter than the colonies of this species already described by Herdman 

 (1886), Hartmeyer (1911) and Kott (1954). Another colony is 3 cm. long and 1-5 cm. in thickness, 

 being of a low-dome-like shape. The surface of the colonies is smooth, and the colour grey to buff, 

 with star-shaped markings produced by the regular arrangement of the zooids in circular systems. No 

 sand is present on the surface or within the colonies, and the common test is semi-cartilaginous in 

 texture. 



Zoom (Text-fig. 8 A). The thorax and abdomen together measure about 3 mm. and the post- 

 abdomen is at least as long. Some reserve material (res.) was present in the lower part of the post- 

 abdomen of a few zooids, and this part was frequently bent so as to lie almost parallel to the base of 

 the colony. 



Thorax. There are six moderately developed lobes on the oral siphon, and the atrial siphon has 

 a simple languet. Twelve to fourteen rows, each with about twelve stigmata, are present in the branchial 

 sac, compared with fourteen to sixteen rows in Hartmeyer's and eighteen in Kott's specimens. 



Gut. The gut is typical of the species, with an ovoid stomach having conspicuous areolations which, 

 however, do not project so much as in the specimens described by previous authors. The anus is level 

 with the 8th or 9th row of stigmata. 



Gonads. In a few zooids a small ovary (ov.) was present at some distance below the end of the 

 intestinal loop, and a few poorly developed testis follicles (t.) occurred in a series posterior to the ovary. 



Remarks. All the previous records of this species are from the region of Kerguelen, and the 

 ' Discovery ' specimens therefore extend the range to South Georgia and suggest that the species may 

 have a wider distribution in the Antarctic. 



Distribution. Antarctic (South Georgia), Subantarctic (Kerguelen). 



