PELAGIC BIRD FAUNAS OF THE INDO-PACIFIC OCEANS 473 



Puffijius nativitatis 

 The breeding range forms an extensive area in the central Pacific, 

 both north and south of the equator, and the species is sympatric with 

 P. pacificus. 



Bulweria spp. 

 The origins of Bulweria bulwerii and B. macgillivrayi are obscure. 

 They occupy the subtropical parts of the North Atlantic and North 

 Pacific and extend into the tropical zone of the Pacific. The genus is 

 unknown as yet in the Indian Ocean. The present distribution suggests 

 that it is a reduced remnant of a former widespread group. 



The Pterodroma hasitaia complex 



Murphy and Mowbray (1951, p. 277) offer some very suggestive 

 comments on the relationships of a group of petrels they refer to as 

 the hasitata super-species and which includes the following allopatric 

 forms: hasitata, cahow, phaeopygia, sandwichensis, exterjia, cervicalis 

 and mollis. 



The parent form of the hasitata series appears to be P. mollis of 

 the southern oceans. It has made a tropical transgression in the eastern 

 Atlantic, and relatively unaltered populations now exist at Tristan da 

 Cunha, the Cape Verde Islands and Madeira. From the centres in the 

 north Atlantic there has been further differentiation and on the op- 

 posite side of this ocean there have developed the races hasitata and 

 cahow. The Pacific may have been peopled through the Panama water 

 gap leading to the evolution of the form phaeopygia (at the Galapagos) 

 and sandwichensis (Hawaii). This hypothesis would require the orig- 

 inal tropical transgression of the ancestral mollis in the pre-Pleistocene 

 and the general pattern of speciation would resemble that of the Puj- 

 finus assimilis-lherminieri group. 



If the north Atlantic and north Pacific forms are the result of 

 independent evolutions from a southern ancestor, not involving use of 

 the Panama water gap, the equatorial transgressions may have occurred 

 as late as the Pleistocene glaciations. In this case the southern Pacific 

 sub-tropical forms, cervicalis (Juan Fernandez) and externa (Kerma- 

 decs), might be off-ihoots of this line of development. Solution of the 

 problem awaits more refined taxonomic analysis of the whole group, 

 which is promised us by Murphy and Mowbray (ibid., p. 278). 



TJie Pterodroma arminjoniana complex 

 Murphy and Pennoyer (1952, p. 35) consider the four species 

 arminjoniana (including heraldica, alba, neglecta, and ultima), to be 

 closely related. Pterodroma arminjoniana alone occurs in all three 

 oceans, in subtropical waters, and in the Pacific Ocean the four species 

 have a sympatric breeding distribution, which does not extend far into 



