3SO DISCOVERY REPORTS 



7. Notoplites tenuis (Kluge). Figs. 13 C, 15 C. 



Scrupocellaria tenuis Kluge, 1914, p. 608, pi. xxvii, fig. 2. 

 Notoplites tenuis Harmer, 1923, p. 352. 

 Station distribution. Antarctic: Weddell Quadrant, Sts. 39, 190, 366, 371 ; Victoria Quadrant, 

 Sts. 1 65 1, 1652, 1660. 



Geographical distribution. South Georgia; South Sandwich Islands; Palmer Archipelago 

 (Discovery); Wilhelm II Land (Kluge); Oates Land (Terra Nova); Ross Sea (National Antarctic 

 Expedition; Terra Nova; Discovery). 



In these specimens there is considerable variation in the cryptocyst, which may, in 

 adjacent zooecia, be distinctly granular, as figured by Kluge, or almost completely 

 smooth. The spines, scuta and frontal avicularia are very irregularly distributed in the 

 colony, and may be absent from many zooecia ; for example, they are extremely rare in 

 the material from St. 1652. The width of the blade of the scutum varies, so that scuta 

 are sometimes seen which look like a flat spine turning at right angles to its base. The 

 median zooecium at a bifurcation (E of Harmer) occasionally has two scuta, overlapping 

 at the middle of the opesia. Basal and marginal heterozooecia have not been seen. The 

 ovicells of a single colony may be round, as figured by Kluge, or taller and narrower. 

 Oval areas may be present in the lateral walls of the zooecia (see p. 339 above). Testes 

 of the usual type have been seen, consisting of very numerous clusters of cells filling 

 the proximal part of the body-cavity. 



Thirty-one 1 young colonies with ancestrulae have been found. The ancestrula is 

 shallow (almost slipper-shaped) and lightly attached to the substratum by its basal sur- 

 face (Figs. 13 C, 15 C). The opesia occupies the greater part of the frontal surface and 

 is surrounded by spines. One zooecium is budded from the ancestrula. It is erect and 

 its long axis is thus at right angles to that of the ancestrula. It is usually separated from 

 the ancestrula by a joint. One or two zooecia (cf. Figs. 13 C and 15 C) are budded from 

 the distal end of this first zooecium and typical biserial budding follows. A rootlet arises 

 from each zooecium, including the first, but usually not from the ancestrula. These 

 rootlets pass straight down the branch on to the substratum, usually leaving the 

 ancestrula clear, but crossing it in one instance. From examination of older colonies it 

 seems probable that the ancestrula breaks away fairly soon, leaving the colony slung by 

 rootlets, the attachment of the ancestrula to the substratum being loose and the con- 

 nexion between it and the first zooecium fragile. Occasionally the first zooecium has 

 two to four spines, but usually it is typical, having one or none. 



In the material from St. 1652 the first zooecium has in two instances given rise to a 

 lateral zooecium as well as to the distal ones. The lateral zooecium arises at about the 

 level of the proximal end of the opesia, and projects from the lateral wall of the zooecium 

 at right angles. It is jointed near its proximal end, and gives rise to two distal buds. 

 Similar lateral zooecia can also be budded from some of the subsequent zooecia. In the 



1 Ancestrulae were obtained as follows : two from St. 39, 25 March 1926; four from St. 366, 6 March 1930; 

 three from St. 371, 14 March 1930; six from St. 1652, 23 January 1936; one from St. TN 339, 24 January 

 1912; five from St. TN 340, 25 January 1912; eight from the east end of the Barrier (National Antarctic 

 Expedition), 29 January 1902; two from McMurdo Sound (National Antarctic Expedition), 13 February 1902. 



