INTRODUCTION. XXI 



the counties lying nearest to them on the mainland of Britain, 

 we still perceive a marked disparity in the number of species 

 produced on areas of equal extent in both, the balance being in 

 favour of the latter or continental districts. The same relative 

 paucity of species obtains in the Channel Islands of Guernsey 

 and Jersey as compared with the adjacent coast of France ; and 

 this inequality of distribution becomes more obvious the greater 

 the interval betwixt the islands and the main, and the smaller 

 the area of the insulated territory. Even with the advantage 

 of climate which a more genial latitude affords, the Flora of 

 small islands, very remote from larger or from continents, is 

 poorer in species than that of other islands of greater extent 

 and less perfect isolation, though lying under a colder parallel. 

 Thus the whole group of the Azores, although pretty com- 

 pletely explored by the labours of Watson, Hochstetter and 

 others, produces little more than one-third the number of phae- 

 nogamous species afforded by the Isle of Wight, notwithstand- 

 ing their more southerly position, and the far greater variety of 

 elevation which the mountainous surface of some amongst them 

 presents for the extended multiplication of species. * 



The Channel Islands, though not rich in species for their 

 size, have, in consequence of their less extent and greater dis- 

 tance from the mainland, a more completely insular or mari- 

 time Flora than the Isle of Wight, as the absence from that 

 group of the following rather inland or continental genera and 

 species, found in the latter island, will testify : — 



Clematis Vilalba Speciilaria hybrida 

 Thalictrum flavum Ehamnus catharticiis 

 Campanula (omnes) Frangula 



* Mr. H. C. Watson, in his 'Catalogue of Azorian Plants' (see Hooker's 

 ' London Journal of Botany' fur November, 1844), makes the total number of 

 flowering species amount to 319, and of ferns to 31, or 350 species in all. A 

 large proportion even of these are common to England and the Azores, and, 

 though some plants no doubt remain unrecorded inhabitants of those islands, 

 the above census cannot be very far short of the number actually existing 

 therein. Even in the tropical Island of Barbadoes, the catalogue of phtenoga- 

 mous species and ferns, enumerated by Sir R. Schomburgh, amounts to but 896, 

 and of these not above one-half would seem to be indigenous, the rest being 

 chiefly plants cultivated for ornament or use, with a few that have become 

 naturalized. 



