260 



FIRST YEAR SCIENCE 



119. Life on Islands. Islands which rise from the conti- 

 nental shelves were probably at one time connected with 

 the continents, but have since been separated by the sub- 

 mergence of the intervening lowland. The animals and 

 plants of such islands are similar to those of the adjacent 

 large land masses. But oceanic islands possess only those 

 types of plants and animals which originally were able to 

 float or fly to them over the surrounding water expanse. 

 Indigenous mammals, except certain species of bat, are 

 wanting. Birds are abundant. 



On the tropical islands the cocoanut palm is the main 

 supply of vegetable food, clothing and building material. 

 Many of the species of both plants and animals are differ- 

 ent from those of the nearest continent and even of the 

 adjacent islands. So complete has been the isolation of 



the life of these islands 

 for so long a time 

 that it has been possible 

 for great differences in 

 species to develop. Large 

 unwieldy birds unable 

 to fly or ruii rapidly 

 have been found on some 

 oceanic islands, the dodo 

 of Mauritius, now ex- 

 tinct, being one of the 

 most notable. 



The absence of pred- 

 atory animals has probably made the development of such 

 forms possible. The great species of tortoise from the Gala- 

 pagos Islands perhaps owes its development to the same 

 cause. Nowhere else have such huge tortoises been found. 

 The remarkable fauna and flora found on oceanic islands 

 may be regarded as due to their geographical isolation. 



THE DODO. 



Although the dodo is extinct, sufficient 



remains have been found to enable 



scientists to tell how it looked. 



