CORMORANTS 



805 



poueh, and they must be considered as descendants of New- 

 Zealand forms, as they are more specialised. If this is correct, 

 the wliite bars on the wings and back must have been lost by 

 P. verrucosus. 



If there is any truth in these speculations, it follows that our 

 third group of cormorants came into the Southern Ocean by 

 South America, whence they spread to New Zealand. Here they 

 underwent considerable alteration, and the altered forms 

 re-migrated to South America, and some, at last, found their way 

 to Kerguelen Island. "When these wide migrations took place, 

 there was probably more Antarctic land than there is at present, 

 but it must have been in the shape of islands, otherwise the South 

 American land birds would have migrated with the cormorants. 



The following is the supposed genealogical tree of the sub- 

 genus Leucocardo : — 



Ranfnrlyi 



Verrucosus 



I 

 Albiventer 



Onslowi 



I 



Carunculatus 



I 



Stewarti 



I 

 Colensoi 



I 



Campbelli 



I 



Magellanicus 



Chalconotus 



Kerguelen Island. 

 South America. 



New Zealand. 



South America, 



P. carunculatus has lost its crest, P. chalconotus and P. traversi 

 have lost the white dorsal bar, and P. ranfurliii has lost caruncles, 

 crest, and dorsal bar. 



Coming back to the origin of the variations, it may be asked, 

 "How did they arrive?" The white bar was a new character 

 acquired by P. colensoi, and the white dorsal bar another new 

 character, first acquired by P. stewarti. It is impossible to 

 suppose that they were caused by amphimixis, as the blending of 

 the sperm and the ovum could not have produced characters 

 that never existed in any of the ancestors of either parent. Nor 

 can the white bars be attributed to the action of the environment, 

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

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



