Buller. — Illustrations of Darwinism. 



95 



bands of colour, and reaching at maturity to a length of 2ft. 



or more.* 



But, although these are good illustrations of the correlation 

 of colour and of the extinction of well-established forms 

 in the struggle for existence, I feel that I am rather digressing 

 from the real subject of my address. 



Closely connected with this subject of assimilative colour- 

 ing is that of the gradual adaptation of structure to the con- 

 ditions of existence. In my " Birds of New Zealand'' I have 

 called attention to some remarkable cases of this kind, and 

 notably to that of the Huia (Heteralocha acutirostris) — an 

 instance quite unique in the whole class of Birds — where the 

 sexes present differently-formed bills, specially adapted to their 

 habits of life and general economy. Now, on what principle 

 apart from the Darwinian theory can we explain this remark- 

 able sexual difference ? 



And to mention another case, that of the Wry-billed 

 Plover (Anarliynchus frontalis) is a very remarkable one. In 

 this instance the bird has the bill turned or twisted to the 

 right, this asymmetry being admirably adapted to this plover's 

 peculiar mode of feeding among the pebbles of the seashore. 

 In the case of our beautiful Eed-necked Avocet (Recurvirostra 

 iiova-lwllandice) , the curvature of the bill is upwards instead 

 of sideways ; and in both forms this marvellous departure 



* It is significant that the Long-tailed Cuckoo (Eadynamys tait* 

 ensis), whose streaming tail-feathers are handsomely barred in their 

 whole length with chestnut and black, is also known by the name of 

 Kawekaweau in many parts of the country. In like manner the name 

 Kakariki (indicative of the colour) is applied alike to the green lizard and 

 to the Green Parrakeet of our woods. 



