ISOLATION 179 



pink or orange. Of the first group three species 

 P. carbo, P. sulcirostris, and P. melanoleucus are 

 also found in Australia; and the fourth P. varius 

 is closely allied to an Australian species. The 

 fifth P. sulcirostris has been developed in New 

 Zealand. The second group consists of ten species^ 

 all of which are confined to New Zealand and its 

 islands, but have relations in Antarctic countries. 



P. brevirostris is a very variable species, incapable 

 at present of breeding truly ; while P. melanoleucus, 

 from which it has been derived, is not variable. P. 

 brevirostris is acquiring a black breast and abdomen ; 

 but, although the young are black, the adults often 

 get white on the abdomen, like P. melanoleucus. 

 Evidently this change to black is not a recognition 

 mark, for the birds often lose it when they approach 

 the breeding age. Neither can the black abdomen 

 be taken to be a useful character. Cormorants have 

 no enemies in New Zealand, so it cannot be de- 

 fensive, and black cannot be better than white for 

 fishing, for most of the cormorants have white 

 abdomens. That the young should be black and 

 not the adult is perhaps due to reversion to P. 

 pygmaeus, of the Mediterranean and Central Asia, 

 from which P. melanoleucus is probably derived. 



Of the second group, two P. punctatus and P. 

 featherstoni have orange legs and a double crest. 

 One inhabits New Zealand, the other the Chatham 

 Islands. The remaining eight species have pale pink 

 legs, and the crest is either single or absent. They 

 may be divided into a carunculated section con- 

 taining P. carunculatus in New Zealand, P. onslowi 



