414 THE DISTRIBUTION OF ANIMALS AND PLANTS 



that they represent to our modern eyes the unmodified descend- 

 ants of continental birds of the early Tertiary. Darwin re- 

 marks that they are remarkably sombre in colouring for equa- 

 torial birds ; but perhaps their ancestors came from a cooler 

 climate, and have not been able to don a tropical garb ; or 

 perhaps they belong to a far-back age, when the vegetable king- 

 dom also was less rich in colouring than it is at present, and 

 the birds were in harmony with it. This, indeed, seems still 

 to be the character of the Galapagos plants, which Darwin 

 says have "a wretched, weedy appearance," without gay flowers, 

 though later visitors have expressed a more favourable opinion. 



These plants are in themselves very remarkable, for they are 

 largely peculiar species, and are in many cases confined to par- 

 ticular islands, having apparently been unable to cross from one 

 island to another, though in some way able to reach the group. 

 The explanation is that they resemble North American plants, 

 and came to the Galapagos at a time when a wide strait sepa- 

 rated North and South America, allowing the equatorial cur- 

 rent to pass through, and drift plants to the Galapagos, where 

 they have been imprisoned ever since. This was probably in 

 Miocene times, and when we know more of the Miocene flora 

 of the southern part of North America we may hope to recover 

 some of the ancestors of the Galapagos plants. In the mean- 

 time their probable origin and antiquity, as stated by Wallace, 

 render unnecessary any hypothesis of modification. 



Before leaving this subject, it is proper to observe that on 

 the continents themselves there are many remarkable cases of 

 isolation of species, which help us better to understand the 

 conditions of insular areas. The " variable hare " of the 

 Scottish highlands, and of the extreme north of Europe, appears 

 again in the Alps, the Pyrenees, and the Caucasus, being in 

 these mountains separated by a thousand miles of apparently 

 impassable country from its northern haunts. It no doubt ex- 

 tended itself over the intervening plains at a time when Europe 



