278 ISLAND LIFE 



and these physical conditions have had a powerful 

 influence on the animal and vegetable forms by which the 

 islands are now inhabited. The Galapagos have also, 

 during three centuries, been frequently visited by 

 Europeans, and were long a favourite resort of buccaneers 

 and traders, who found an ample supply of food in the 

 large tortoises which abound there ; and to these visits we 

 may perhaps trace the introduction of some animals whose 

 presence it is otherwise difficult to account for. The 

 vegetation is generally scanty, but still amply sufficient for 

 the support of a considerable amount of animal life, as 

 shown by the cattle, horses, asses, goats, pigs, dogs, and 

 cats, which now run wild in some of the islands. 



Absence of Indigenous Mammalia and Amphibia. — As in 

 all other oceanic islands, we find here no truly indigenous 

 mammalia, for though there is a mouse of the American 

 genus Hesperomys, which diff'ers somewhat from any known 

 species, we can hardly consider this to be indigenous ; first, 

 because these creatures have been little studied in South 

 America, and there may yet be many undescribed species, 

 and in the second place because even had it been intro- 

 duced by some European or native vessel, there is ample 

 time in two or three hundred years for the very different 

 conditions to have established a marked diversity in the 

 characters of the species. This is the more probable 

 because there is also a true rat of the Old World genus 

 Mus, which is said to differ slightly from any known 

 species ; and as this genus is not a native of the American 

 continents we are sure that it must have been recently 

 introduced into the Galapagos. There can be little doubt 

 therefore that the islands are completely destitute of truly 

 indigenous mammalia ; and frogs and toads, the only 

 tropical representatives of the Amphibia, are equally 

 imknown. 



Reptiles. — Reptiles, however, which at first sight appear 

 as unsuited as mammals to pass over a wide expanse of 

 ocean, abound in the Galapagos, though the species are not 

 very numerous. They consist of land-tortoises, lizards and 

 snakes. The tortoises consist of two peculiar species, 

 Testudo microphyes, found in most of the islands, and T. 



