466 EIGHTH PACIFIC SCIENCE CONGRESS 



The main categories should be divided into primary and secondary 

 elements, where they can be clearly recognised as such. In this paper 

 I have attempted this only for the Pan-Tropical Fauna. In the cases 

 of the other two faunas the ranking of most of the species or species 

 groups is evident from the context. 



The principal pelagic bird faunas in the Indo-Pacific region may, 

 accordingly, be classified into the following categories on the basis of 

 distributional and probable evolutionary patterns: 



2. SOUTHERN ELEMENTS. 



Ekman (1953, p. 229) holds that the antarctic shelf has been a 

 centre of development for marine animals for a long period of time: 

 "a cold climate has continued without disturbance from the transition 

 between the Cretaceous and the Tertiary Periods into recent times," 

 thus accounting for its richness of species. Proceeding northwards from 

 the antarctic various faunal sub-divisions are recognisable to the sub- 

 tropics and Ekman, on the basis mainly of invertebrate studies, re- 

 cognises the following: Antarctic, Antiboreal (cold temperate), and 

 Warm Temperate. 



Murphy (1936, p. 71) has shown how different species of pelagic 

 sea-birds characterise the different hydrological zones of surface water. 

 His work has demonstrated how various elements of the southern fauna 

 have adapted themselves to varying degrees of coldness, and one can 

 conveniently speak of the birds of the Antarctic Zone, those of the Sub- 

 Antarctic Zone and those of the Sub-Tropical Zone. Some are not so 

 restricted but in several cases the convergences between these water 

 masses represent real boundaries between breeding ranges. Closely 

 allied species and sub-species are representative of different zones. 



PENGUINS 



No Penguin has penetrated into the temperate waters of the 

 Northern Hemisphere, but Spheniscus mendiculus of the Galapagos 

 region, has reached the Equator as a breeding species and actually ranges 

 north of it. 



ALBATROSSES 



These birds are another highly characteristic southern group. The 

 few species in the North Pacific are the descendants of trans-equatorial 

 colonists and will be considered as secondary elements of the Tropical 

 Fauna. 



PETRELS 



Fulmarus glacialis and F. glacialoides 

 The northern Fulmar breeds in the Pacific in the Kurile Islands, 

 Bering Sea and Aleutian Islands, and in the Atlantic in Baffin Land, 



