EDWARD FORBES. 217 



the primrose, the buttercup, the lesser celandine, and, 

 in fact, our ordinary flowering-plants, together with our 

 common shrubs and trees. Some of the less abundant 

 species of this general flora are confined to the eastern 

 counties of England, and a considerable number of 

 common English types are not found to occur in Ireland. 



The question next arises how can the above remark- 

 able facts as to the distribution of plants in Britain be 

 accounted for? In attempting the solution of this 

 problem, Forbes points out three modes in which an 

 isolated area (such as the British Islands) might become 

 in the first place peopled by plants or animals : 



(1) By special creation within the area. 



( 2 ) By transport to it. 



(3) By migration before isolation. 



The first of these modes needs no consideration, as the 

 British animals and plants, taken as a whole, are identical 

 with those of the continent of Europe, and there is there- 

 fore no necessity, and indeed no room, for the supposition 

 that they were specially created for our area. 



The second mode, namely introduction to the region by 

 transport, is insufficient. Supposing Britain to be, as it 

 now is, separated from the Continent, artificial or natural 

 means of transport might doubtless serve to explain the 

 existence with us of certain animals and plants ; but 

 it assuredly would not adequately account for the dis- 

 tribution of the general flora and fauna of our country. 



The third hypothesis, therefore, alone remains namely, 

 that our animals and plants have been introduced by 

 migration before isolation. In other words, our present 

 animals and plants have, in the main, simply reached us 



