88 



CHAPTERS ON EVOLUTION. 



FIG. 27. PENGUIN. 



closely imitated amongst ourselves by the Aylesbury duck although, 

 indeed, the young ducks are able to fly. The wing of the penguin 

 (Fig. 27) is a mere scaly appendage utterly useless for flight, but 



useful as a veritable fin, 

 enabling it to swim under 

 water with great facility ; 

 and of the auk's wing the 

 same remark holds good. 

 In the birds, then, there is 

 ample evidence of dete- 

 rioration of organs in the 

 rudimentary nature of the 

 wings of many species. 

 How these conditions have 

 been brought about is not 

 difficult to explain in 

 most instances. In New" 

 Zealand, where we find a 

 singular absence of quad- 

 rupeds, wingless birds 

 many being extinct of 

 which the Apteryx is a 

 good example, take the 

 place of the four-footed population. In view of an immunity from 

 the attack of other animals, the ground-feeding habits of these 

 birds would become more and more strongly settled as their special 

 way of life ; and in the pursuit of such habits, the wings, seldom used 

 for flight, would- degenerate as time passed. The later advent of 

 man, in turn, has exterminated certain races of the wingless birds 

 such as the Dodo (Fig. 28) and Solitaire (Fig. 29) in Mauritius and 

 Rodriguez whilst the wingless and giant Dinornis of New 

 Zealand, and its contemporaries, have probably been hunted to 

 the death of their species, by their human co-tenants of these 

 strange lands. 



The ascent to the quadrupeds brings in review before us still 

 more striking illustrations of the apparently incomplete rendering of 

 the structures of animal life. No better instance of the " rudimen- 

 tary organs " of the naturalist can be found than in the group of the 

 whales, and more especially in the species from which we obtain the 

 commercial whalebone and oil the Greenland or Right Whale. 

 This whale possesses no teeth in its adult state, but before birth 

 teeth are found in the gum. These teeth, however, are gradually 

 absorbed, and utterly disappear from the jaws, the adult whale 

 possessing, as is well known, a great double fringe of " whalebone-" 

 plates depending from the palate. The same remark holds good of 



