68 Da^'zvin, and after Darwin. 



dwindling due to inutility. Thus, for example, to 

 return to the case of wings, we have already seen 

 that in an extinct genus of bird, Dinornis^ these 

 organs were reduced to such an extent as to leave 

 it still doubtful whether so much as the tiny rudiment 

 hypothetically supplied to Fig. 6 (p. 6i) was present 

 in all the species. And here is another well-known 

 case of another genus of still existing bird, which, as 

 was the case with Dinomis, occurs only in New 

 Zealand. (Fig. 9.) Upon this island there are no four- 

 footed enemies — either existing or extinct — to escape 

 from which the wings of birds would be of any service 

 Consequently we can understand why on this island 

 we should meet with such a remarkable dwindling 

 away of wings. 



Similarly, the logger-headed duck of South America 

 can only flap along the surface of the water, having 

 its wings considerably reduced though less so than 

 the Apter-yx of New Zealand. But here the interesting 

 fact is that the young birds are able to fly perfectly 

 well. Now, in accordance with a general law to be 

 considered in a future chapter, the life-history of an 

 individual organism is a kind of condensed recapitu- 

 lation of the life-history of its species. Consequently, 

 we can understand why the little chickens of the 

 logger-headed duck are able to fly like all other ducks, 

 while their parents are only able to flap along the 

 surface of the water. 



Facts analogous to this reduction of wings in birds 

 which have no further use for them, are to be met 

 with also in insects under similar circumstances. 

 Thus, there are on the island of Madeira somewhere 

 between 500 and 600 species of beetles, which are in 



