492 DISCOVERY REPORTS 



p. 255). The restriction of bottom-living animals to particular habitats in more or less 

 limited regions has been shown by various ecological surveys; but I think the possi- 

 bility of a close correlation with hydrology of the wider geographical distribution of a 

 group, whose members are not only bottom-living but fixed, has not been generally 

 recognized. Detailed analysis of this relationship might explain some of the apparent 

 anomalies of distribution. 



DISTRIBUTION OF THE GENERA 



From Table 3 (p. 479) we see that fourteen genera of Cellularine Polyzoa are repre- 

 sented in the hydrologically Antarctic region south of the Antarctic convergence. 



Two of these (Tricellaria and Menipea) are represented by only two species, and only 

 penetrate the northern part of the Antarctic area. Bugula, which otherwise has an almost 

 world-wide distribution, is represented in the Antarctic area by a single rather aberrant 

 species, B. longissima. The genus is also almost completely absent from sub-Antarctic 

 waters, B. hyadesi being the only species recorded. 



Consideration of the distribution of Brettia and the two new genera, Klugella and 

 Erymophora, must wait till further revision of other faunas gives us a reliable list of the 

 species to be included. 



This leaves eight Antarctic genera whose distribution can profitably be discussed. 

 Six of these, Amastigia, Notoplites, Farciminellum, Cornucopina, Himantozoum and 

 Camptoplites, are predominantly Antarctic and sub-Antarctic. The other two, Beania and 

 Caberea, are distributed almost throughout the world. Beania has several sub-Antarctic 

 species, and two Antarctic ones, namely, B. erecta, which is common, and B. scotti, 

 known from a single fragment. Caberea is represented in our area by a single, widely 

 distributed, variable species, C. darioinii (see p. 382), and by C. rostrata which is found 

 at Tristan and New Zealand. 



The distribution of the six predominantly Antarctic genera is summarized in the 

 maps (Figs. 61-66). The numbers on the maps represent the number of species recorded 

 from each locality. Species from depths greater than 1000 m. are indicated by figures 

 on black circles. A list of the species that I have included in the genus is given with 

 each map, with a reference to the page in the report where the distribution of each 

 species is to be found. Where the distribution is not included in this report a reference 

 is given. 



In each genus we find at least one species that is very widely distributed in the 

 Antarctic, at least one shallow-water sub-Antarctic form, and a few deep-water species 

 extending farther north, particularly in the Atlantic and the Malay Archipelago. This 

 completes the story of the distribution of Camptoplites, 1 but the other genera are more 

 widely dispersed. Notoplites, which is found in deep water in the Atlantic, appears 

 again in shallow boreal and Arctic waters, and Amastigia is known from South Africa ; 

 but only three 2 species in all the six genera are recorded in shallow water from America 



1 See Addendum, p. 501. 



2 Including Cornucopina antillea Osburn from 732 m. 



