AMASTIGIA 329 



length and some have as many as six. The inner rows of zooecia contribute more to the 

 basal surface than in A. cabereoides, and the frontal surface is correspondingly less 

 convex. The branches (Plate VII, fig. 1) thus appear broader and flatter than those of 

 A. cabereoides. In other features, including the basal vibracula and the occasional 

 gigantic frontal avicularia, the two species are similar. The ovicells are like those of 

 A. cabereoides, as figured by Kluge. The short stout spines, two on the side opposite 

 to the scutum and one on the other, are proximal to the ovicell. The relation of this 

 species to A. cabereoides is comparable to that of A. nuda to A. gaussi (see p. 325). 



8. Amastigia antarctica (Kluge). Fig. 5 A. 



Anderssonia antarctica Kluge, 1914, p. 618, pi. xxxiii, figs. 3, 4. 

 Amastigia antarctica Harmer, 1923, p. 338. 



Station distribution. Not represented in the Discovery collections. 



Geographical distribution. Wilhelm II Land (Kluge); Oates Land (Terra Nova); Ross Sea 

 (Terra Nova ; National Antarctic Expedition). 



There are a few fragmentary specimens agreeing very closely with Kluge 's descrip- 

 tion of this species. The basal surface is usually entirely formed by the lateral zooecia, 

 but part of the specimen from the National Antarctic Expedition's winter quarters 

 (no. 10 hole) is 7-serial, and here the median zooecia reach the basal surface forming 

 a broad continuous band. The intermediate series are still completely excluded, or only 

 just visible. In other species of Amastigia in which the median and intermediate zooecia 

 are more or less excluded from the basal surface, they take fairly equal shares in the 

 formation of the basal wall, giving a more or less regular lozenge-pattern (e.g. Harmer, 

 1923, pi. xvii, fig. 24). The ovicells (Fig. 5 A) are rather flatter and straighter sided than 

 those shown by Kluge. The calcified part of the ectooecium forms a narrow band on 

 each side to which the avicularia of the distal zooecium are attached, and the mem- 

 branous part appears to be continuous with the frontal membrane of the distal 

 zooecium. 



As pointed out by Harmer (1923, p. 339), A. antarctica is allied to A. pateriformis 

 (see below), which is represented in the British Museum by the very small type- 

 colony. In the latter the frontal avicularia, which are unpaired even on the median 

 zooecia, are set very obliquely, or almost transversely, and may be of large, but not 

 gigantic, size. In A. antarctica they are paired on the median zooecia and are usually 

 smaller, though the unpaired ones on the lateral zooecia may very much resemble those 

 of A. pateriformis. The basal heterozooecium in A. pateriformis is placed at the extreme 

 proximal end of the exposed part of the basal wall of the zooecium to which it is attached. 

 In A. antarctica the basal wall of the zooecium usually extends a short distance beyond 

 the heterozooecium proximally, as shown by Kluge, and the heterozooecium is smaller, 

 but one specimen (from St. TN 194) has larger, more oblique ones, some of which 

 extend to the proximal end of the exposed part of the basal wall of the zooecium. 

 The median zooecia are not completely excluded from the basal surface of the branch 

 in A. pateriformis. It will be seen that none of these differences is absolutely constant, 



