334 Royal Institution. 
the Eastern American States, these authors conceive can only be 
explained by assuming such direct overland connexion of the two 
continents. 
The speaker explained the basis upon which comparisons between 
two recent floras and between a recent and fossil flora should rest, 
referring to the peculiar conditions which affect 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 Pro- 
fessor Heer*, about 800 species of Phanerogamia have been dis- 
covered, referable to 197 genera (exclusive of Phyllites, Carpolithes, 
&e.), of which number 145 still exist. Of these genera— 
76 are common to the Swiss tertiary, 
and to the present flora of . . Europe. 
77 : : ‘ : ; . Japan. 
88 ; . : : ; . United 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 
tertiary, as Glyptostrobus, numerous Fici, coriaceous-leaved oaks 
and Lauraceae, Juglandee, Liquidambar, &c. 
The genera common to the Swiss tertiary and the United States, 
which are not found also in the old world, are Sabal, Taxodium, 
Bumelia, Liriodendron, Ceanothus, Ptelea, and Carya. But in 
respect to these 7 it was observed that at least 5 were very doubtful 
determinations. The 9 largest orders of the ‘ Flora Tertiaria Hel- 
vetize’ are Leguminose, Amentacea, Cyperacee, Proteaceae, Lau- 
racee, Gramineae, Coniferea, Composite, and Aceracee. Of these 
Orders 3 are included in the 9 largest of Europe, 4 in the 9 largest of 
the United States, and 6 in the 9 largest of Japan, while the re- 
maining 3 of the tertiary, not included in the 9 largest orders of 
Japan, are much more largely developed in Japan than in the 
United States. They are Lauraceae, Aceracee, and Proteaceae. 
The proportion of ligneous to herbaceous species in the above 
floras was alluded to. Heer estimates ligneous plants to have 
formed about 66 per cent. of the phanerogamic vegetation of the 
tertiary in Switzerland. The speaker considered this estimate as too 
high, believing that sufficient allowance had not been made for the 
advantages that ligneous plants, which are often tall-stemmed, possess 
over herbaceous species in securing access of their leaves and débris 
to the waters in which they had been floated and ultimately pre- 
served. He admitted, however, that ligneous species were relatively 
very numerous in the vegetation of the tertiary period. The pro- 
portion of ligneous plants he estimates in the existing flora of Japan 
at near 40 per cent., in the Southern States 22, Northern States 18, « 
Europe 9 to 12. * 
* The Tertiary data were throughout derived from the ‘Flora Tertiaria 
Helvetize’ of Professor Heer, 
