870 ISLAND LIFE part ir 



many other stations which, so far as we can judge, seem 

 equally suitable to them. Yet it is a curious fact, that 

 the* phenomena of distribution actually presented by this 

 group do not essentially differ from those presented by 

 the higher flowering plants which have apparently far 

 less diffusive power, as we shall find Avhen we come to 

 treat of the floras of oceanic islands ; and we believe 

 that the explanation of this is, that the life of species, and 

 especially of genera, is often so prolonged as to extend over 

 whole cycles of such terrestrial mutations as Ave have 

 just referred to ; and that thus the majority of plants are 

 afforded means of dispersal which are usually sufficient 

 to carry them into all suitable localities on the globe. 

 Hence it follows that their actual existence in such 

 localities depends mainly upon vigour of constitution and 

 adaptation to conditions just as it does in the case of the 

 lower and more rapidly diffused groups, and only partially 

 on superior facilities for diffusion. This important principle 

 will be used further on to afford a solution of some of the 

 most difficult j^roblems in the distribution of j^lant life.^ 



Concluding Jxemeirks on the Peculiarities of the British 

 Fauna and Flora. — The facts, now I believe for the first 

 time brought together, respecting the peculiarities of the 

 British fauna and flora, are sufficient to sliow that there is 

 considerable scope for the study of geographical distribu- 

 tion even in so apparently unpromising a field as one of 

 the most recent of continental islands. Looking at the 

 general bearing of these facts, they prove, that the idea so 

 generally entertained as to the biological identity of the 

 British Isles with the adjacent continent is not altogether 

 correct. Among birds we have undoubted peculiarities in 

 at least three instances ; peculiar fishes are much more 

 numerous, and in this case tlie fact that the Irish species 



^ While these pages are passing tliiougli the jiress I am iulbniied li}' my 

 Mend Mr. W. fl. Beeby that in the Shetland Isles, where he has been 

 collecting lor live summers, he lias found sev'eral plants new to the British 

 flora, and a few altogether iindescribed. Among these latter is a very 

 distinct species of Hieracium {H. Zetland Icioii), which is (luite unknown 

 in Scandinavia, and is almost certainly peculiar to the British Islands. 

 Here we have another proof that entirely new species are still to be dis- 

 covered in the remoter portions of our country. 



