44 THE DARWINIAN THEORY 



198 varieties of the common wood-snail have been 

 described. In the case of insects, many of our 

 common English butterflies vary enormously. 

 Among birds, a remarkable series of facts is 

 quoted by Wallace, from a memoir by Mr. Allen 

 on the birds of Florida. Exact measurements were 

 taken of large numbers of these, and all parts were 

 found to vary; not only were variations of 15 to 

 20 per cent in actual and relative sizes found 

 ordinarily; but the variations affected the length 

 and breadth of the tail and wings; the length, 

 width, depth, and curvature of the bill, the form of 

 the toes, the intensity of colour and nature of the 

 markings. This was therefore not a case of minute 

 or infinitesimal variations, but variations on a large 

 scale, affecting all parts and in all directions. 



Variation in habits. — A good illustration of the 

 variation which may occur in habits is found in the 

 Kea, a curious parrot inhabiting the mountain ranges 

 of the island of New Zealand, and feeding naturally 

 on the honey of flowers, on insects, fruits and 

 berries, which till quite recently comprised its 

 whole diet. However, since the European occupa- 

 tion of the island, this bird has acquired a taste for 

 carnivorous diet with alarming results. It began by 

 picking the sheep-skins hung out to dry, or the meat 

 in process of being cured. In 1865 it was first 

 observed to attack living sheep, which were fre- 

 quently found with raw and bleeding wounds in 

 their backs. Since then it is stated that the bird 

 actually burrows into the living sheep, eating its 

 way down to the kidneys, which form its special 



