482 EIGHTH PACIFIC SCIENCE CONGRESS 



siderably. The cases that have suggested themselves to me are as 

 follows: 



Parent Form Southwest Pacific race 



Puffinits pacificiis chlororynchus P. p. pacificus 



Puffinus assimilis haurakiensis P. p. kermadecensis 



Pelagodroma marina maoriana P. m. nlbichinis 



It is possible that the same isolating mechanisms may have been 

 responsible for the break which led to the differentiation of the two 

 Grey Noddies, Procelsterna cerulea in the north and P. cinerea in the 

 south. After its evolution P. cinerea embarked on an explosive colo- 

 nisation through the South Pacific. 



Speculating even more daringly one might attribute the evolution 

 of Sterna lunata from the presumed ancestral S. anetheta to the same 

 factors. The two forms may have now overlapped each other in the 

 Southwest Pacific through secondary invasion. 



Attention may be directed here to a further subspeciation centre, 

 in New Zealand, and south of the tropical-subtropical area just re- 

 ferred to. In the New Zealand region, including its southern islands, 

 active speciation is shown by the Crested Penguins {Eudyptes chryso- 

 chome and allies), albatrosses {Diomedea bulleri and cauta), Puffinus 

 bulleri (an ally of P. pacificus) and two subspecies of the Cookilaria 

 group of Pterodrotna. If one includes southeastern Australia Puffinus 

 tenuirostris enters into the picture as a \exy close ally of P. griseus. 



It would appear that in this general area, with its rich develop- 

 ment of local species and subspecies outstanding in the Indo-Pacific— 

 a complex system of isolating mechanisms has been at work. The only 

 worker who has attempted an analysis is Fleming (1941a, pp. 146, 152) 

 who has sought the explanation in a "movement of the hydrological 

 convergences due to past climatic cycles and perhaps paleogeographic 

 changes," the suggested causative factors being "changes in the intensity 

 of Antarctic glaciation during the late Tertiary and Pleistocene." The 

 field warrants further prospecting, in particular a deeper study of local 

 modifications of the ocean current system which Fleming regards as 

 responsible for some present-day anomalous distributions in the Aus- 

 tralian and New Zealand region. 



V. Literature Referred to in the Text 



Alexander, W. B., 1928. Birds of the Ocean, New York. 

 Austin, 0. L., 1952. Notes on some petrels of the North Pacific. Bull. Mus. 

 Comp. ZooL, vol. 107, No. 7, pp. 391-407. 



