SLW COLONIAL fLORAS. ^O 



than there are to the West Indies and Asia ; the approximate numbers 

 being, of the former 210, and of the hitter 220. Of the aggregate 

 number, upwards of 200 are common to Africa and Asia, leaving a 

 very few common to Africa and the AVest Indies, and not hitherto 

 found in Asia. Of these the following are, as being large trees, the 

 plants of most interest in this inquiry : — 



American trees that have migrated to Africa ; or vice versa. 

 Carapa Gruianensis. 

 Paullinia pinnata. 

 Loncbocarpus sericeus. 

 Drepanocarpus lunatus. 

 Hecastophyllum Brownii. 

 Andina inermis. 

 Chrysobalanus Icaco. 



Of these seven, four belong to one Natural Order, Leguminosm, 

 and most of these, together with probably all the rest, are more or 

 less littoral plants. 



Under whatever light we regard this fact, it appears a very strong 

 argument against their being much oceanic and aereal transport of 

 seeds between the tropics of the Eastern and Western worlds ; and, 

 coupled with the no less remarkable counter-fact, that there are many 

 more marked points of affinity between the Floras of the extra- tropical 

 regions of America and Africa (though these are so very much more 

 distant geographically), than between the tropical Floras of these 

 countries, it would at first-sight appear to throw us back upon an- 

 cient continental extension, to accouat for much of the community of 

 vegetation, which we do find to exist between the tropics of the Old 

 and New Worlds. But sufficient ancient continental extension demands 

 incalculable time to account for ; and one effect of this, if granted, 

 must be great specific and even generic change on the descen- 

 dants of the species that lived on the common continent. The 

 question, therefore, next to be asked is, whether there is greater 

 generic affinity between the West Indies and Africa, than between 

 the West Indies and Asia? Here again we 'are baffled, there being 

 only 50 genera common to the former case, but 53 in the latter ! ; 

 besides which, there are a considerable number of large and impor- 

 tant Natural Orders common to the West Indies and xisia, that are 

 almost wanting, or comparatively very rare, in tropical Africa ; such 

 are LaurinecB, IlagnoUacece, Ilgristicece, Ilicinece, Guttiferce, Buta- 

 cece, Gesneriacece, Vacciniece, ConifercB, Orchidece, Falmece, PiperacecB. 



