THE UllJEl' O LEO VnO ROUS FAUN.IJ. 



nearer India than Cliili, has more affinity with the latter than the 

 former. The Cape-Verde Islands, although so near Cape Verde, 

 have tlieir affinity not with Africa, but with Europe and the other 

 Atlantic Islands. Even in the introductions by man it does not 

 apply. Hear what DeCaudolle says of plants. " I am surprised 

 that the commerce of the United States, with Brazil, Chili, New 

 Zealand, the Sandwich Islands, and China, a commerce which has 

 been carried on witli great activity for upwards of thirty years, 

 has not yet brought about the naturalization of species from these 

 regions. Up to the present time there is no appearance of it. 

 The BuUeva multifida, which has begun to appear at New York, 

 and of which the naturalization is not yet consolidated by the proof 

 of time, is the only plant perhaps which has come in this manner. 

 In future some will arrive, without doubt." [Why so ? Surely 

 not from what has happened in the past?] " They may compen- 

 sate to some extent perhaps the probable diminution of those 

 which will come from Europe"*. 



Facts are accuuiulating upon us to show that diffusion of plants 

 and animals by accidental circumstances beyond physical barriers, 

 such as seas or impassable mountains or deserts, bears no import- 

 ant part in the establishment of any definite fauna or flora. They 

 bear a part, although a small one, in the introduction of occasioual 

 new elements into a fauna or flora ; but these remain like lumps 

 of stone lying on a soil with which they can neither become in- 

 corporated nor harmonize, usually readily distinguishable and re- 

 ferable to the mountains or strata more or less distant from which 

 they have come. Actual continuity of soil and non-interruption 

 by barriers is, I believe, the only cause by which any fauna with 

 a definite character (and no true fauna is without one) has been 

 produced, and subsequent isolation, at least so far as regards phy- 

 sical conditions, that by which it has been preserved. The coral 

 islands of the Pacific are a case in point. They have been sup- 

 l)lied both with a fauna and flora entirely from without and by 

 chance dispersal ; and they furnish an admirable example of the 

 kind and amount of inhabitants that is to be got by such intro- 

 ductions, even under the most favourable circumstances of tran- 

 quil seas, warm climate, and favouring currents ; and allowance to 

 such an extent I am always ready to make in examining the ele- 

 ments of any fauna or flora. The details of such a fauna and 

 flora will be given further on when I come to discuss the fauna of 

 * DcCancloUe, G6ogr. Botuniquc raisonnee, p. 755 (1855). 



