302 THE ANIMALS OF NEW ZEALAND 



They may be divided into three ijronps. The first consists of 

 five species, three of which are also found in Australia, and they 

 can be distino^uished by their black legs and feet. The second 

 group contains only two species, both endemic, which have yellow 

 or orange legs and feet, and a double crest on the head. The 

 third group consists of eight species, all peculiar to New Zealand 

 seas; and these have pink or reddish leg's and feet, and the 

 crescent is either single or absent. 



The first group evidently comes to us from the north. The 

 pied shag, which is one of the two endemic species, is closely 

 related to Plialacrocorax goiihU and P. liypoleucus of Australia. 

 The second endemic species is P. hrevirostris. This and P. 

 melanoleucus, which occurs in the Moluccas, Australia, and New 

 Caledonia, are so closely related, and have so many intermediate 

 links, that some naturalists are inclined to consider them as 

 varieties of one species. The geographical distribution of the 

 birds leads to the belief that P. hrevirostris is descended from P. 

 melanoleucus, and the latter from P. pijgmaeus of the Mediter- 

 ranean and Central Asia. There is confirmatory evidence of this 

 in the fact that hrevirostris is a very variable species, apparently 

 not yet capable of breeding truly, while P. melanoleucus is not 

 variable, but is an old and well established species. 



The curioiTS point in regard to this question is in connection 

 with the plumage of P. hrevirostris and that of its ancestors. 

 P. pygmaeus is black, with scattered white plumes on the head, 

 back, and abdomen ; P. melanoleucus is black above and white 

 below, with a white frill on each side of the neck ; but P. hrevi- 

 rostris is black, with a white chin and throat. If, therefore, the 

 evidence from geographical distribution, and from variability, can 

 be trusted, the descendants of P. pygmaeus, as tliey travelled 

 southwards, acquired a pure white breast and abdomen. But 

 when some individuals reached New Zealand, there was a new 

 change, the breast and abdomen becoming black. 



Some ornithologists would explain these variations in P. 

 hrevirostris as cases of partial albinoism, or of intercrossing 

 with P. melanoleucus. But if the variations are due to albinoism, 

 it might be expected that the white would appear on the upper 



