30 THE MEANING OF EVOLUTION 



similar beach marks on the sheer western face of the 

 Andes, and found them without difficulty, confirming 

 his idea of the recent rise of this end of the Andean 

 chain. 



The Beagle continued its voyage up the western 

 coast of South America until it reached Peru. Once 

 more the abundance of tropical life is under Darwin's 

 eyes, but now it is the life of an entirely different 

 section. The dry climate of Peru furnished him with 

 an environment distinctly unlike that of the moist Bra- 

 zilian forest. He collects now with avidity, gather- 

 ing especially insects and birds. Then the ship turned 

 its prow westward across the Pacific, only to stop five 

 hundred miles out at the Galapagos Islands. This 

 little group he studied intensely, collecting large num- 

 bers of insects and birds. He had not worked over 

 his collection long before he realized that each island 

 in the group had peculiarities which marked its ani- 

 mals from those of any other island. Whenever two 

 islands were close together in the group the differ- 

 ences in their fauna were found to be comparatively 

 slight. If, however, he examined the animals from 

 two islands lying at opposite ends of the group, the 

 differences were always considerably greater. There 

 was, however, a strong general resemblance among 

 them all and a distant though not so strong resem- 

 blance to the corresponding animals of the Peruvian 



