Scott 41 informs us, is only a little more primitive than 

 Erethizon, the change from the one to the other involving 

 but a slight modification. 



Erethizon is unknown in Xorth America from pre-' 

 Pleistocene deposits, but there is no reason to assume 



existed in western Xorth America from early Tertiary 

 times onward without having left their remains in the 

 more ancient deposits. 



The theory of the former existence of a great lobe of 

 land connecting western Xorth America with southern 

 South America during the beginning of the Tertiary era, 

 while Central America and northern South America were 



affinities prevailing 

 than by any other 

 «d that it is an im- 



plant at least, Sequoia semper virens, has lived without 

 any appreciable change down to the present time from 

 those remote ages. And even if we altogether eliminate 

 the testimony elicited from a botanical source, there still 

 remain zoological factors of importance as buttresses of 

 the hypothetical bridge I have constructed. 



