EVIDENCE FROM DISTRIBUTION 123 



mals, the bones of which are preserved in such 

 natural museums as the wonderful asphalt pits near 

 Los Angeles: horses, tapirs, llamas, elephants and 

 mastodons, giant ground-sloths, huge wolves, lions, 

 the terrible sabre-tooth tigers, and countless others. 

 Here is a zoological revolution, which equally af- 

 fected the northern part of the Old World. 



We have very clear proof that the form, size and 

 mutual connections of the various continents have 

 undergone a long succession of changes. In the 

 cases where two continents, now connected, were 

 formerly separated by the sea, the proof of this 

 separation almost always remains in the form of 

 marine deposits, including the fossils of marine 

 animals. In this manner the ancient disjunction of 

 North and South America, the separation of the 

 Spanish peninsula from Europe, of north Africa 

 from the remainder of the continent and of India 

 from Asia, may be readily demonstrated. On the 

 other hand, in the case of those lands which were 

 formerly connected, but now are separated by the 

 sea, the direct proof is wanting, because the connec- 

 tion is covered by the sea, but soundings generally 

 indicate it, for most of the former connections which, 

 for one reason or other, we presume to have existed, 

 are marked out by areas of shoal water in very sharp 

 contrast to the profound depths of the oceanic 

 abysses. Such former connections are indicated 

 between Alaska and northeastern Asia, Great 

 Britain and the continent of Europe; Spain and 



