6 HUTTON, The Cormorant a of New Zealand . [istjuly 



The earliest known fossil Cormorants are from the upper 

 eocene in England, and there are miocene species in France 

 and in Patagonia. At this time we know that the land route 

 from Australia to New Zealand had been broken up. But could 

 the birds have spread from South America to New Zealand 

 under the present conditions ? I think not, because the crossing 

 from New Zealand to the neighbouring islands, or from the 

 islands to New Zealand, must be very rare, and none have 

 spread into Polynesia. Cormorants cannot be blown to sea 

 like land-birds, and when these wide migrations took place 

 there must, I think, have been more antarctic land than now. 

 But this must have been islands only, or else the South 

 American land-birds would have migrated with the Cormorants. 



Again, as to the origin of the variations. The white alar bar 

 was a new character acquired by P. colensoi, and the white 

 dorsal bar another new character first acquired by P. stewarti. 

 How did they arise ? Not by amphimixis. It is impossible 

 that the simple blending of the sperm and ovum could have 

 produced characters which never existed in any of the ancestors 

 of either parent. Nor by the action of the environment, because 

 it is impossible to connect the origin of white feathers on the 

 wings and back with the weather or with any of the surrounding 

 objects ; especially as in P. chalconotus the changes have been 

 in the opposite direction, and not only have the white alar and 

 dorsal bars been lost, but the whole of the under surface has 

 turned black. P. chalconotus and P. stewarti live together in 

 Stewart Island, and even inhabit the same shaggeries, so that 

 it is impossible that these opposite variations could have been 

 caused by external conditions. 



Can we account for them by sexual selection ? Take, for 

 example, the origin of the white alar bar in P. campbelli, or the 

 white dorsal patch in P. stewarti, which, being new characters, 

 cannot be due to reversion. What right have we to suppose 

 that a preference was shown, by individuals of the opposite sex, 

 to one that had some white feathers on its wing or back. And 

 even if we do allow this, what guarantee is there that successive 

 generations would all show the same preference ? Why should 

 not some prefer wholly black individuals ? And if they did, 

 the selection would be destroyed and the variation would not 

 accumulate. I do not remember to have seen this objection 

 to sexual selection noticed before, but it is evidently a very serious 

 one. The bright colours of the skin on each side of the face 

 in Cormorants will be looked upon as a typical example of sexual 

 selection ; but the same difficulty occurs here also. Why should 

 both sexes prefer the same colours in their partners as they have 

 themselves, although they cannot see their own colours ? And 



