EXPLANATIONS. 



iar Flora or Fauna occupying a certain geographical area 

 in the ocean would be apt to become the common source 

 of the Flora or Fauna of any masses of land adjoining to 

 it. Now we shall see how the facts harmonize with this 

 view. Wherever there is a group of islands standing 

 much apart, its plants and animals are never found allied 

 to those of any remote region of the earth, but invariably 

 show an affinity to those of the nearest larger masses ot 

 l?md. Thus, for example, the Galapagos exhibit general 

 characters in common with South America ; the Cape 

 de Verd islands, with Africa. They are, in Mr. Darwin's 

 happy phrase, satellites to those continents in respect of 

 natural history. Again, when masses of land are only 

 divided from each other by narrow seas, there is usually 

 a community of forms. The European and African shores 

 of the Mediterranean present an example. Our own 

 islands afford another of far higher value. It appears that 

 the flora of Ireland and Great Britain is various, or rather 

 that we have five floras, or distinct sets of plants, and 

 that each of these is partaken of by a portion of the oppo- 

 site continent. There are, 1st, a flora confined to the 

 west of Ireland, and imparted likewise to the north-west 

 of Spain ; 2d, a flora in the south-west promontory of 

 England and of Ireland, extending across the Channel to 

 the north-west coast of France ; 3d, one common to the 

 south-east of England, and north of France ; 4th, an Al- 

 pine flora developed in the Scottish and Welsh High- 

 lands, and intimately related to that of the Norwegian 

 Alps ; 5th, a flora which prevails over a large part of 

 England and Ireland, " mingling with the other floras, 

 and diminishing, though slightly, as we proceed west 

 ward;" this bears intimate relations with the flora of 

 Germany. Facts so remarkable would force the merest 

 fact-collector or species-dei) miinator into generalization 

 The really ingenious man who lately brought them under 

 notice,* could only surmise, as their explanation, that the 

 spaces now occupied by the intermediate seas must have 

 Deen dry land at the time when these floras were created. 

 In that case, either the original arrangements of the floras, 

 or the selection of land for submergence, must have been 

 apposite to the case in a degree far from usual. The ne- 

 cessity for a simpler cause is obvious, and it is found in 



* See a paper, read by Professor Edward Forbes, at Cambridge 

 »sune, 1845, in Literary Gazette, No. 1484 



