ix.] PALAEONTOLOGY AND EVOLUTION. 217 



and I am inclined to believe that it continued along the 

 eastern side of the Pacific area to what is now the province 

 of Austro-Columbia, the characteristic fauna of which is 

 probably a remnant of the population of the latter part 

 of this period. 



Towards the latter part of the Mesozoic period the 

 movement of upheaval around the shores of the Atlantic 

 once more recommenced, and was very probably accom- 

 panied by a depression around those of the Pacific. The 

 Vertebrate fauna elaborated in the Mesozoic continent 

 moved westward and took possession of the new lands, 

 which gradually increased in extent up to, and in some 

 directions after, the Miocene epoch. 



It is in favour of this hypothesis, I think, that it is 

 consistent with the persistence of a general uniformity 

 in the positions of the great ' masses of land and water. 

 From the Devonian period, or earlier, to the present day, 

 the four great oceans, Atlantic, Pacific, Arctic, and Ant- 

 arctic, may have occupied their present positions, and 

 only their coasts and channels of communication have 

 undergone an incessant alteration. And, finally, the 

 hypothesis I have put before you requires no supposition 

 that the rate of change in organic life has been either 

 greater or less in ancient times than it is now ; nor any 

 assumption, either physical or biological, which has not 

 its justification in analogous phenomena of existing 

 nature. 



I have now only to discharge the last duty of my 

 office, which is to thank you, not only for the patient 

 attention with which you have listened to me so long to- 

 day, but also for the uniform kindness with which, for 

 the past two years, you have rendered my endeavours 

 to perform the important, and often laborious, functions 

 of your President a pleasure instead of a burden. 



