SUMMARY AND CONCLUSION 297 



anccd such statements ; and in the second place, even 

 admitting the identifications to be correct, there is no 

 evidence whatever to disprove that these genera have 

 not spread north and south respectively from an equa- 

 torial base — suffered extermination in Europe, but still 

 survive in Australia. I might here take the opportunity 

 of remarking, that in a great many cases these equa- 

 torial range bases must for obvious reasons have been 

 entirely obliterated, as species have moved north and 

 south from them, and become resident types in higher 

 latitudes. 



The Andes and the Rocky Mountains, stretching in 

 one almost continuous line from the Arctic to the 

 Antarctic regions, are stated by Dr. Wallace " to have 

 formed the most effective agent in aiding the southward 

 migration of the Arctic and North Temperate vegetation." 

 Now, for the sake of argument, we must presume that 

 the equatorial or torrid portions of this continuous 

 mountain chain (and also by analogy of <•?// other moun- 

 tains and highlands within the torrid zone) held a flora 

 of some kind, suited to the requirements of a very 

 elevated cool climate, before any glacial epoch came on 

 to drive these imaginary Arctic plants southwards. There 

 is perfectly uncontrovertible evidence to prove that 

 before glaciation the lands in North Polar latitudes con- 

 tained a luxuriant flora, even of a semi-tropical char- 

 acter, and that therefore no " Arctic " or " Scandinavian" 

 flora could have existed dominantly in those latitudes, 

 if at all. If they did so exist, " iji no one case has a single 

 example of sncJi a f anna orjlora been discovered of a date 

 anterior to the last Glacial Epoch!' (The italics are mine.) 

 As the climate slowly changed and cold conditions came 



