468 EIGHTH PACIFIC SCIENCE CONGRESS 



Near allies of this species appear to be Pterodroma brevirostris, of 

 the sub-antarctic islands of the southern Indian Ocean sector, and P. 

 inexpectata, of temperate and sub-antarctic islands of the New Zealand 

 area, and a trans-equatorial migrant to the north Pacific. 



Murphy and Mowbray (1951, p. 277) place P. mollis as a member 

 of a series of tropical petrels which they call the hasitata super-species, 

 and which is referred to in a later section. 



STORM-PETRELS 



Pelagodroma marina 



A temperate and subtropical species, which has transgressed the 

 equatorial belt only in the Atlantic. It is the third member of a series 

 of southern petrels— Puffinns assimilis and Pterodroma mollis being the 

 others— which has established itself at the Canary and Cape Verde group 

 of islands. In the Pacific Ocean it has penetrated as a breeder only as 

 far north as the Kermadecs, but as a foraging wanderer it has been col- 

 lected southwest of Cocos Is. (Lat. 4° 31' N.) and off Ecuador. 



In the Indian Ocean it nests as far north as the Abrolhos Islands 

 in southwest Australia. 



Fregetta grallaria 



Apparently not found in the Indian Ocean but widely ranging in 

 the southern Pacific and Atlantic Oceans, north to the tropics. 



GULLS 



Southern gulls have only a peripheral distribution along the South 

 American continent and in the Australian and New Zealand region. 

 There has been virtually no colonisation of insular habitats. Creagrus 

 furcatus, of the Galapagos, is a strongly marked exception and is pre- 

 sumably an old species. 



All gulls probably have an ultimate origin as members of the 

 northern fauna and southern forms are the results of a series of equa- 

 torial transgressions. Murphy (1936, p. 1041) has indicated in regard 

 to South American species that "the connection between the coastal 

 gulls of the northern and southern hemispheres is much closer in the 

 Pacific than in the Atlantic," and it is inferred that the colonising route 

 lay along the eastern Pacific. 



Larus dominicanus is interesting in being the only representative 

 of the large gulls in the southern hemisphere and in possessing (in 

 conjunction with its Australian derivative, pacificus) a circumpolar 

 distribution in sub-antarctic and warm-temperate seas. Opinion differs 

 as to whether it is derived from the northern L. marinus (Wetmore) or 

 L. fusciis (Dwight). Murphy and Falla are of the opinion, based on 

 voice and behaviour, that dominicanus is a black-backed argentatus 

 (pers. comm.) 



