REPTILES 43 



Baur to be the causes of the present differentiation. Such a 

 joining together into one island of all the islands of the archi- 

 pelago, including the northern islands of Wenman and Culpep- 

 per, would necessitate an elevation of more than 7,000 feet. 

 Furthermore, a connection with the American continent is 

 thought necessary by the same authority to explain the origin 

 of the fauna and flora of the archipelago. Such connection 

 with the continent would require an elevation of more than 

 10,000 feet, the present altitude of the islands having been 

 attained through a corresponding submergence, a possible 

 though improbable submergence, from the steep character of 

 the adjacent South American coast which has been rising 

 through a long period of geologic time. 



Doubtless the assumed submergence is amply sufficient to 

 account for the faunal characteristics of the archipelago but it 

 is unnecessary and at variance with geological and biological 

 evidence as illustrated in the derivation of the life of other similar 

 groups of islands. Nearly all groups of volcanic islands exhibit 

 similar though perhaps less striking differentiation of the species 

 inhabiting separate islands. Since nearly all have been popu- 

 lated by strays from the present continental masses or from other 

 islands we do not see the necessity of making the Galapagos an 

 exception. Almost all authors from Darwin to Rothschild and 

 Hartert, have regarded the Galapagos as a group of oceanic 

 islands, Dr. Baur alone adopting the subsidence theory. 



As a group the Galapagos Archipelago is probably today of 

 greater extent than at any earlier geologic period though much 

 erosion and perhaps some subsidence has taken place. The 

 larger volcanoes are extinct, volcanic activity at present being 

 confined to small lateral vents which in recent years have added 

 only slightly to the size of the islands on which they occur. The 

 northern portion of Abingdon, much of Narboro and Bindloe, 

 some of the western portions of Albemarle and the southwestern 

 part of James appear to be due to rather recent lava flows. 

 Evidences of elevation appear at various localities. Near Iguana 

 Cove, Albemarle there are several old sea cliffs now situated a 

 considerable distance inland. At Tagus Cove on the same island 

 a series of terraces, still containing the characteristic cavities 



