OLITEE ON THE ATLATfTIS HYPOTHESIS. 1G5 



latitudes.* Professor Heer himself says,t " Comme les types japon- 

 nais occupent line place importante dans notre flore tertiare, il est 

 permis de supposer qu'a I'epoque tertiare le Japon etait joint an 

 contiaent Americain." — Tlie general character of the Tertiary Flora 

 appears to me to be almost as conspicuous,— in some respects more 

 conspicuous — in Japan than in the American States. We have 

 shown that of the nine largest orders numerically of the Tertiary, six 

 are included in the nine largest of Japan, and but four in the nine 

 largest of the Southern States ; while, farther, the remaining three 

 of the nine largest Tertiary orders are much more developed in Japan 

 than in the Southern States. They are 



Lauracese, in Japan 11 gen. 25 species. In So. States 4 gen. 6 species. 

 Aceraceae „ 2 „ 15 „ „ 2 „ 6 „ 



Proteacese „ 1 „ 1 „ „ „ „ 



The Japanese flora is the only one which I have found presenting 

 such close correspondence in this respect with that of the Tertiary 

 period. In Australia 5, India 4, Europe 3, and in the New World 4, J 

 of the largest orders of each respectively, are included in the cor- 

 responding nine of the Tertiary. Nor must the large percentage of 

 ligneous species in the Japanese (40 per cent.) as compared with 

 the Southern United States flora (22 per cent.) be overlooked. 



That the Tertiary element should be more decidedly expressed in a 

 comparison of the genera in Eastern Asia than in the American States, 

 is by no means required unless we can show that its development 

 and persistence have been equally favoured by climatal and other 

 conditions in both regions since the Tertiary period. It might have 

 been fairly expected, moreover, that on Professor Heer's hypothesis, 

 the North American element in the Flora of the Atlantic islands 

 should have been more decided, favourable as would appear to be 

 their climate to the growth of the plants of the Southern States ; 

 but we do not find in these Islands more of this element than 

 they might have derived from Eiu'ope during a connection with 

 it in, or subsequent to, the Tertiary period. With regard to 

 the few American species mentioned by Dr. A. Grray§ as occurring 

 in Western Europe, and opposed to the view that the inter- 



• Prof. Goeppert says, (Bull. Ac. Imp. St. Petersburg, iii. 460, 1861), " Wenn 

 vvir nun die ausgedehnte Verbreitung der schon jctzt im Polarkreise auf den Aleuten, 

 in Gronland, Island, Kamtschatka nachgewiesenen Flora der Miocenen formation 

 betrachten, die sich vielleicht auch noch iiber das nordlichste Amerika auf Nord- 

 Siberien und die luseln des Eismeeres erstreckt * * * * so diirfen wir wohl 

 annebmen, dass in jenen jetzt so unwirthlichen Gegenden zur zeit der Miocen 

 periode ein milderes Klima, etwa eine mittlere Temperatur von mindestens 8-9" dort 

 herrschte, um eine Vegetation zu fdrdeni, wir sie gegenwartig in mittleren und 

 siidlicheren Nordamerika und Europa angetroifen wird." 



t Recherches, &c., p. 216. 



t The principal orders of these four areas I have taken from Dr. Hooker's 

 " Introductoiy Essay to the Flora of Tasmania," p. xxxv. 



§ 1. c. 442. 



