166 OEIGINAL AETICLES. . 



cliange of European and New "World forms had taken place via 

 Asia, viz. Eriocaulon septangulare, Betula alba, Spartina and Suhu- 

 Inria, — to wliicli I may add Naias Jlexilis (a common North Ame- 

 rican plant, but extremely rare in Europe, which I discovered in 

 Connemara some twelve years ago), it may be observed that all of 

 these, save the common birch, are aquatic or littoral salt-marsh 

 plants. Wlieu we recall the observation of Mr. Darwin relative to 

 the number of seeds often contained in the mud of ponds, &c., 

 the wandering habits of wading birds, and the chances favoiiring the 

 dispersal of aquatic sjjecies,* no argument can be based upon them 

 of any weight compared with the preponderance of evidence in favour 

 of an Asiatic migration aflbrded by the relatively large number of 

 existing types peculiar to E. America and the eastern margin of the 

 Old World, as compared with the few peculiar to America and 

 Europe. Why Betula alba should be included among the above 

 species I am at a loss to understand. It grows across Europe, in the 

 Altai and Amoorland. Subularia also extends eastward to the Altai, 

 according to Ledebour. 



1. Samyda. One species of Unger's occurs in the Swiss beds. I 

 have not seen any true Samyda with the lateral veins nearly so 

 numerous and approximate : it may be a Casearia, but this is ex- 

 tremely doubtful. 



2. Banisteria and Hircea rest u2)on very imjjerfect materials. 

 They cannot be satisfactorily determined from Professor Heer's 

 figures. The same is also true of Coriaria. 



3. PifeZea— resting upon single foliolae or indeed single leaves, 

 cannot be satisfactorily accepted in the absence of the dry and easily 

 preserved fi-uits. The leaflet figured as P. Weberi certainly much 

 resembles a lateral one of P. trifoliata. The genus is placed in 

 ZantJtoxylece by Dr. Hooker. 



4. Sterculia tenuinervis, Heer, stated to resemble S. Labrusca, 

 Ung., and compared as to form and direction of the leaf-lobes with 

 S. (Firmiana) platanifolia, L. resembles the trilobate form of this 

 species very fairly. S. platanifolia, however, is not an American, 

 but a Chinese and Japanese plant. S. modesta is very doubtful. 



5. Apeibopsis. With fruits 5 to 16-valved, and leaves described 

 as palmiuerved ; but none have been certainly identified with the 

 fruits. Notwithstanding Professor Heer's observations, I consider 

 the affinity of these remarkable fruits yet imsettled. Probably 

 imder this generic term two or more genera may be included. Tab. 

 cxviii., 23, resembles Hura ; fig. 27 an Aristolochia. 



6. Neyundo, rests upon an uncertain identification 



7. Pittosporum. — A determination of Ettingshausen's ; very 

 dubious, as Prof Heer observes, as to the Swiss specimen. Judging 



* Origin of Species, p. .386. Vide, also De Candollc, Gcog. Bot. Kais. p. 519. 



