12 ANIMAL LIFE PAST AND PRESENT. 



armour are, however, quite separate from one another, 

 this arrangement being probably more conducive to 

 freedom of action in swimming. 



The great class of Birds, which Professor Huxley 

 calls only highly modified reptiles, are remarkable in 

 that there is no trace of a coat-of-mail in any single 

 species. And when we come to consider the life which 

 these creatures lead, we at once see the absence of any 

 need for such a protection. Thus it is quite clear that 

 in ordinary birds, which are gifted with the power of 

 flight, a bony armour would not only be perfectly un- 

 necessary as a protection, but would also seriously im- 

 pede, if indeed it did not totally prevent, their flight. 

 On the other hand, in the flightless birds, like the 

 ostriches and their allies, or the kiwis of New Zealand, 

 sufficient protection is afforded either by their size and 

 strength, or by their nocturnal habits. There are, 

 indeed, certain flightless species, like the extinct dodo 

 of Mauritius, which have neither strength nor speed, 

 nor are of nocturnal habits. Their want of the power 

 of flight is, however, an acquired loss, due to their 

 dwelling in islands in which they are, or were, free 

 from the persecution of enemies, and thus needing no 

 special protection of any kind. 



Leaving the birds, we have to complete our survey 

 of the various types of armour obtaining among verte- 

 brate animals by a glance at that class which includes 

 the highest of all vertebrates, and indeed of all animals. 

 Unfortunately we are still in want of a good popular 

 name for this class, which includes man himself. In 



