288 INTRODUCTION TO EVOLUTION 



regions to be." To the hostility of the terrain to shoe leather is added the 

 inhospitable nature of the vegetation: tree cactus, prickly pear cactus, 

 thornbushes. 



As one progresses inland and upward from the coast on the three 

 highest islands extensive areas of open country are found. Humid forests 



90° W. 



85" W. 



80° W. 



90° W. 



83° W. 



80° W. 



FIG. 13.2. Position of the Galapagos Islands. (From Lack, Darwin's 

 Finches, Cambridge University Press, 1947, p. 2.) 



occur in the interiors of the larger islands. Altogether, then, the archipelago 

 exhibits considerable variety of habitat. 



Despite the fact that the islands are directly under the equator, the cli- 

 mate is not excessively hot. The ameliorating effect of the cold Peruvian 

 current sweeping northward along the coast of South America accounts 

 for this fact in large measure. 



Reptiles 



The archipelago receives its name from the giant land tortoises which 

 form some of the most distinctive inhabitants. These huge reptiles, weigh- 

 ing up to 500 pounds, were formerly abundant but are now becoming 

 scarce. Their tameness, coupled with their ability to stay alive for months 

 in the holds of buccaneer and whaling vessels, furnishing a supply of fresh 

 meat in prerefrigeration days, contributed to their downfall. Darwin re- 

 corded, "It is said that formerly single vessels have taken away as many 

 as seven hundred, and that the ship's company of a frigate some years since 



