OF ISLAND FAUNAS 149 



have stout heavy bodies. They are very partial to 

 cactuses, but also climb the acacia trees to feed upon 

 the foHage. 



Closely related to Conolophus, and therefore like it 

 one of the iguana family, is the marine hzard Ambly- 

 rhynchus cristatus. It also is entirely pecuhar to the 

 islands, and is the only hzard known which is marine 

 in habitat. It inhabits the shores of most of the islands, 

 and feeds upon seaweeds which grow below tide mark, 

 and, as Daxwin proved, it can tolerate prolonged im- 

 mersion without any iU effects. It will be recollected 

 (cf. p. 116) that the typical iguanas are forest animals. 

 The exceptional conditions to which the forms in the 

 Galapagos Islands are exposed has made it necessary 

 for these to adopt modified habits. 



The family Iguanidae is further represented in the 

 islands by various pecuhar species of the genus Tropi- 

 durus, other members of which occur on the continent 

 of South America. Various species of geckoes belong- 

 ing to the widely distributed genus PhyUodactylus also 

 occur, most of these being pecuhar to the islands. 

 There are also two snakes, both being nearly aUied to 

 South American forms. 



Amphibians are entirely absent. Of the inverte- 

 brates the insects are few in number, but show the same 

 characters as the other kinds of animals. In other 

 words, most of the species and many genera are pecuhar, 

 and the forms tend to have a hmited distribution 

 among the islands, very few being found in aU the 

 islEmds. Further, there are many wingless forms, 

 a common feature in island insects. 



It is not necessary to describe the fauna of other 

 islands of the same type as the Galapagos archipelago 

 in detail, for the general characters are the same in 



