224 GLIMPSES OF NATURE. 



with Madagascar itself. But the Mascarene tortoises 

 have been shown to differ from the Galapagos ones, 

 and there are thus practically no traces of these huge 

 reptiles to be found near to the last-named islands 

 themselves. Accordingly, taking his stand upon the 

 general theory which accounts for the immigrant- 

 population of volcanic islands, Dr. Giinther tells us 

 that the Galapagos tortoises are probably of American 

 origin. They came from the continent, in short, which 

 has given to the Galapagos Islands their other forms 

 of life. 



There is, besides, no difficulty in accounting for the 

 passage by sea of these animals. They are very 

 tenacious of life, and many tortoises emulate their 

 turtle-neighbours in the fact of their taking freely to 

 water. Doubtless the original parents or ancestors of 

 the big reptiles of the Galapagos Islands were drifted 

 out to sea by some flood which swept them from their 

 land-haunts. A mass of driftwood may have formed 

 a raft on which they would easily exist for days and 

 weeks without food. Once stranded on the Galapagos 

 shores, these reptiles would find themselves very much 

 at home ; and would settle down as colonists in these 

 lonely isles of the sea. 



It must be noted, however, that animals thus trans- 

 ported to foreign shores show that tendency to variation 

 in form and habits which is so widely represented in 

 all the children of life. We know, for instance, that 

 as regards many islands of the Mediterranean Sea the 

 lizards found thereon, which are identical as species 

 with those of the mainland, nevertheless develop 

 different colours in their island habitations. They 

 usually become blue or black in tint. As regards the 

 lizards of the Seychelles Archipelago, naturalists can 



