308 



THE ANIMALS OF NEW ZEALAND 



useful characters only; and considerable doubt has been thrown 

 on sexual selection. It is too often the custom now-a-days to 

 think that we have discovered all the processes working in 

 organic nature, and that the doctrine of utilitarianism will, in 

 some way or other, explain everything ; and, when any difficulty 

 arises, it is attributed to our ignorance of details, not of prin- 

 ciples. These difficulties, however, must be faced; and it is 

 possible that a close and impartial study of specific characters will 

 destroy our complacency, and show that there is some principle 

 of definite variation at work which preserves non-adaptive 

 characters. 



Key to tlw Species. 



The Black Shag.— Kawau. 



Fhalacrocorax carho. 



Above, black, glossed with blue or green, bronzy on the back. Below 

 greenish black; the throat and a band extending to the eye, white. A 

 white patch on the thigh, and many linear white feathers on the head 

 and neck when in full breeding plumage. Skin round the eye, greenish 

 brown; beneath the eye and chin, yellow. Legs and feet, black. Eye, 



