1862. J Prof. Oliver on the Distribution of Northern PlanU. 431 



WEEKLY EVENING MEETING, 



Friday, March 7, 1862. 



The Rev. John Barlow, M.A. F.R.S. Vice-President, 

 in the Chair. 



Pbofessor D. Oliver, 



OF UNIVEBSIir COLLEGE, LONDON. 



On the Distribution of Northern Plants. 



The discourse referred primarily to the botanical evidence bearing 

 upon the hypothesis advanced by Professors Unger * and Heer "f of an 

 Atlantic communication between Europe and America at some period 

 of the tertiary epoch. The close analogy which is to be traced between 

 the miocene flora of central Europe and the existing flora of the 

 Eastern American States, these authors conceive can only be explained 

 by assuming such direct overland connection of the two Continents. 



The speaker explained the basis upon which comparisons between 

 two recent floras and between a recent and a fossil flora should rest, 

 referring to the peculiar conditions which affiect the latter comparison 

 owing to the imperfect and partial character of the fossil element. 

 The general character of the tertiary flora of central Europe was 

 described. In the tertiary beds of Switzerland, according to Professor 

 Heer,J about 800 species of Phanerogamia have been discovered, 

 referable to 197 genera (exclusive of Phyllites, CarpolitheSj &c.), of 

 which number 154 still exist. Of these genera — 



76 are common to the Swiss tertiary, 



and to the present flora of . . Europe. 



77 ...... Japan. 



88 Ditto States, America. 



120 Europe and Asia 



(taken together, and 

 including Japan). 



It is to be noted that the 77 of Japan include 26 not occurring in 

 Europe : amongst them several forms highly characteristic of the ter- 



* * Die versunkene lusel Atlantis.' 

 t * Flora Tertiaria Helvetia?.' 



i The Tertiary data were throughout derived from the 'Flora Tertiaria 

 Helvetise ' of Professor Heer. 



Vol. III. (No. 35.) 2 o 



