CABEREA 387 



of the zooecia and vibracula, in the number of spines, and in the keeled frontal surface 

 of the fertile branches, this variety resembles the Antarctic form of C. darwinii. It 

 differs in the small size of all the frontal avicularia except those on the median zooecia 

 at the bifurcations, and in the large size and characteristic shape of these median 

 avicularia. In the Antarctic form the avicularium on the median zooecium may be 

 larger than the other frontal avicularia, but all are more or less enlarged and of 

 similar shape so that there is not the marked contrast that is found in this variety 

 (cf. Fig. 24 A, B). 



Coming from the region of the Falkland Islands and showing so many of the charac- 

 teristics of the Antarctic type var. guntheri seems at first sight to disagree with the distri- 

 bution of C. darwinii as summarized on p. 383 . The stations at which the variety replaced 



-5mm 



Fig. 24. A. Caberea darwinii Busk, Antarctic type. National Antarctic Expedition, McMurdo Sound. 

 B. C. darwinii var. guntheri var.n. St. WS 840, between Burdwood Bank and Patagonian Shelf. Both 

 drawings show the zooecia immediately preceding a bifurcation. In Fig. B the scutum of the median 

 zooecium is broken, and the granulation of the cryptocyst has been omitted from all but one of the 

 zooecia. 



c. cryptocyst, mdb. mandible, op. operculum (open), sp. spine, v. vibraculum. 



the typical form are, however, the deepest from which Polyzoa were obtained in the 

 Patagonian region, and there is some reason to think that they are influenced by 

 Antarctic conditions (see p. 486). 



The form from Juan Fernandez figured by Marcus (19210:, p. 98, text-fig. la) as 

 C. rostrata (see p. 390 below) also has a giant avicularium before the bifurcation, with the 

 chamber spreading proximally, but with a longer mandible, and no pointed prolongation 

 of the chamber. Spines are more numerous than in var. guntheri, and the zooecia are 

 smaller and have a smooth cryptocyst with no marked proximal widening. The scuta 

 are similar in shape and have a distal connexion, as in C. darwinii, but the condyle-like 



