A NATURALIST IN BRAZIL 



the larynx is in some respects not unlike the lower larynx of 

 the bird. 



But both the squirrels and the monkeys have visible as well as 

 audible tokens by which to recognize their kind. On the whole, 

 they are more brilliantly coloured than the other mammals ; black, 

 white and yellow are often seen ; one species of Howler Monkey is 

 red, while the Silver Monkey is dressed in gleaming silvery white, 

 from which his flesh-coloured face and dull black tail stand out 

 conspicuously. At the same time, the monkeys have improved the 

 mammalian face, inasmuch as the eyes have been brought together, 

 so that an object can be seen by both eyes at once, which makes it 

 possible for the monkey to obtain a perspective, and indeed a 

 stereoscopic view of the object ; and this is necessary for such estimates 

 of distance as must be made in springing from bough to bough, or 

 jumping across a stream. The horse, which is unable to fasten both 

 eyes on an object, cannot judge distances so well, and this explains 

 why he is given to shying. This juxtaposition of the eyes has of 

 course affected the nose, so that the improvement of the face has 

 resulted in a diminution of the sense of smell ; but this, as we have 

 seen, is not so important in the case of arboreal animals as in that 

 of the terrestrial species. 



The adaptation begun by the monkeys has been completed by 

 the birds. They are true arboreal and aerial animals; from early 

 morning to sunset they are in almost uninterrupted movement; 

 their blood temperature is higher than that of the mammals, and 

 their sense of smell has degenerated, though sight and hearing are 

 for that reason all the more fully developed. 



No greater contrast can be imagined than that afforded by passing 

 from the mammal's gallery in a museum to that of the birds. Here, 

 suddenly, we come upon creatures resplendent with colour, enhanced 

 here and there by metallic lustre. I have already spoken of the 

 dazzling colours of the Brazilian birds ; they are indeed incomparably 

 splendid. And these colours are not merely effective when close at 

 hand ; on the contrary, they are heightened by the movements of 

 the bird, by the rays of sunlight that fall upon it, by the changing 

 character of the background. One is actually startled when a 

 Scarlet Tanager flies out of a thicket ; the sudden appearance of 

 the living ruby is too unexpected for a European. However com- 

 fortably I might be sitting in my rocking-chair in the balcony of 

 my room in the OUnda monastery, and however interesting the 

 book in my hand, the excited twittering — zip^ ivUi, zibui, zibiii, zibiii^ 



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