COLOURS OF ANIMALS. 163 



distinguished in this respect, from the temperate 

 species. 



It is true that brilliant tropical birds mostly belong to 

 groups which are wholly tropical as the chatterers, 

 toucans, trogons, and pittas ; but as there are perhaps 

 an equal number of groups which are wholly dull- 

 coloured, while others contain dull and bright-coloured 

 species in nearly equal proportions, the evidence is by 

 no means strong that tropical light and heat have any- 

 thing to do with the matter. But there are other groups 

 in which the cold and temperate zones produce finer- 

 coloured species than the tropics. Thus the arctic ducks 

 and divers are handsomer than those of the tropical 

 zone ; while the king-duck of temperate America and 

 the mandarin-duck of North China are the most beau- 

 tifully coloured of the whole family. In the pheasant 

 family we have the gorgeous gold and silver pheasants 

 in North China and Mongolia ; and the superb Impeyan 

 pheasant in the temperate North- Western Himalayas, as 

 against the peacock and fire-backed pheasants of tropical 

 Asia. Then we have the curious fact that most of the 

 bright-coloured birds of the tropics are denizens of the 

 forests, where they are shaded from the direct light of 

 the sun, and that they abound near the equator where 

 cloudy skies are very prevalent ; while, on the other 

 hand, places where light and heat are at a maximum 

 have often dull- coloured birds. Such are the Sahara 

 and other deserts, where almost all the living things are 

 sand-coloured ; but the most curious case is that of the 

 Galapagos islands, situated under the equator, and not 

 far from South America where the most gorgeous colours 

 abound, but which are yet characterized by prevailing 



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