472 EIGHTH PACIFIC SCIENCE CONGRESS 



(b) Secondary Elements of Ultimate Southern Origin 

 ALBATROSSES 



It is only in the north Pacific that Albatrosses are found outside 

 of the circumpolar Southern Ocean as breeding species. Murphy (1936, 

 p. 633) considers Diomedea albatrus, D. immiitahilis and D. nigripes 

 a related group and linked, through D. irrorata of the Galapagos, 

 with D. exulans and D. epomophora of the southern albatrosses. The 

 present distribution of the breeding ranges of the Pacific species points 

 to the eastern Pacific being the colonising path but the transgression 

 of the tropics may have been accomplished when a mid-Pacific upwelling 

 zone existed. 



PETRELS 



Pujfinus Iherminieri 

 Mention has been made of the probable derivation of Pujfinus 

 Iherminieri from a P. assimilis stock which made a pre-Pleistocene 

 transgression of the tropics. The subsequent evolution of the Ihermin- 

 ieri group has been essentially as a tropical form and by means of the 

 Panama and Indo-Malayan water gaps it has now populated the Pacific 

 and Indian Oceans. In the Pacific it nests on a multitude of islands 

 in the tropical and sub-tropical areas. Some of these colonies now 

 approach, through secondary contact, very closely to the northernmost 

 nesting colonies of the presumed ancestral species, P. assimilis. 



Puffiniis pacificus 



Pujfinus pacificus belongs to a cluster of species of wholly dark 

 shearwaters of southern waters, but itself is wholly sub- tropical and 

 tropical in distribution. It occurs only in the Indian and Pacific Oceans, 

 but is not found, as a breeding species, in the southeastern portion 

 of the latter ocean. There are two discrete populations, separated by 

 the Indo-Malayan islands and Australia (Fig. 3). These two popula- 

 tions do not, however, coincide with the two sub-species which can be 

 recognised (see later). 



In Western Australia the species breeds from Carnac Island near 

 Fremantle in the south to Sable Island in the Forestier group, in north- 

 western Australia. The species is then absent, even as a forager, along 

 the whole of northern Australia, until we pass Torres Straits, when the 

 first breeding colonies occur on numerous islands to Montague Island in 

 southern New South Wales. 



Pujfinus bulleri, of New Zealand, is a close ally of this species, but 

 which is nearer the ancestral form is uncertain. 



