BAUE’S CEITICISMS 
313 
on the Galapagos and various other islands, Dr. Gadow * asks 
the pertinent question—Where did all these creatures come 
from, and how did they get to these oceanic islands ? Acci¬ 
dental transport is out of the question, as land-tortoises are 
drowned within a few hours after immersion in water. Since 
none of their kind inhabit the great continents now, although 
they lived there formerly, we are constrained to assume that 
the existing species are the survivors of tortoises which pro¬ 
ceeded to the islands when they were connected by land with 
the adjoining continents. In another place Dr. Gadow quotes 
the Galapagos tortoises as supporting the hypothesis of an 
Oligocene extension of land, considerably to the west and 
south of the present Central America. In his maps illus¬ 
trating the palaeogeography of Middle America, he actually 
joins the Galapagos islands with the Antilles, as Professor 
Baur had done, by way of Cocos island.f 
Professor Boettger J approves of the results obtained by 
Professor Baur’s methods of investigation, arguing that the 
facts of distribution are much more easily explained by the 
assumption of a former land connection between the Gala¬ 
pagos archipelago and Central America than by the theories 
hitherto accepted. 
While in general agreement with the same views, Dr. 
Sarasin § suggests that the ancient land bridge lay in a north¬ 
eastward direction, that is to say, from the Galapagos islands 
towards Mexico rather than to Ecuador. 
The fossil marine mollusks and their distribution are em¬ 
ployed by Dr. von Ihering || in support of the same theory. 
He draws attention to the remarkable fact that the species 
of the Tertiary Chilean deposits only appear on the Cali¬ 
fornian coast in Pleistocene times, and that similarly the 
Californian Tertiary forms only reached the coasts of Chile 
about the same time. On these grounds alone Dr. von Ihering 
bases his theory of a Tertiary peninsula extending westward 
into the Pacific Ocean and embracing the Galapagos islands, 
* Gadow, H., “ Amphibia and Reptiles,” p. 373. 
t Gadow, II., “Mexican Amphibians and Reptiles,” p. 211. 
X Boettger, O., “ Baur’s Differentiation of Species,” p. 462. 
§ Sarasin, F., “ Die Fauna der Galapagos Inseln,” p. 293. 
|| Ihering, II. von, “ Fauna der Neotropischen Region,” p.296. 
