132 ESSAYS. 



ing the few cases which point in the opposite direction (e. g. 

 Eriocaulon septangulare, Spartina, Subularia, Betula alba}, 

 the general statement will be seen to be well sustained. Also, 

 in the "Journal of the Proceedings of the Linnaean Society," 

 ii. p. 34, Mr. Bentham " calls to mind how frequently large 

 American genera (such as Eupatorium, Aster, Solidago, Sola- 

 nuni, etc.) are represented in eastern Asia by a small number 

 of species, which gradually diminish or altogether disappear 

 as we proceed westward toward the Atlantic limits of Europe ; 

 whilst the types peculiar to the extreme west of Europe (ex- 

 cluding of course the arctic flora) are wholly deficient in 

 America. These are among the considerations which suggest 

 an ancient continuity of territory between America and Asia, 

 under a latitude, or at any rate with a climate, more merid- 

 ional than would be effected by a junction through the chains 

 of the Aleutian and the Kurile Islands." 



I shall presently state why connection in a more meridional 

 latitude need not be supposed. 



The deficiency in the temperate American flora of forms at 

 all peculiar to western Europe is almost complete, and is most 

 strikingly in contrast with the large number of eastern 

 American forms repeated or represented in eastern Asia. Of 

 genera divided between eastern North America and Europe, 

 I can mention only Ostrya, Narthecium, Psamma, the mari- 

 time Cakile, and perhaps Scolopendrium. Hottonia might 

 have been added, but for a species accredited to Java. And 

 if we extend the range across our continent, we add only 

 Cercis and Lceflingia. Of the ampler genera at all charac- 

 teristic of the European flora, I can enumerate from the flora 

 of the northern United States nothing more important than 

 Helianthemum and Valerianella, two or three species of each 

 (but those of the former hardly congeners of the European 

 ones), adding that Hieracia and perhaps Cirsia are somewhat 

 more plentiful in eastern than in western America. Let it 

 also be noted, that there are even fewer western European 

 types in the Pacific than in the Atlantic United States, not- 

 withstanding the similarity of the climate ! 



That representation by allied species of genera peculiar or 



