INTRODUCTION. xi 



nity of showing the extent of this similarity, and I 

 have endeavoured to exhibit it in the habitats given 

 to the plants enumerated in the Synopsis, for which I 

 am chiefly indebted to Boissier's work on the plants 

 of the south of Spain, a work of such acknowledged 

 reputation, that it would be superfluous in me to 

 recommend it to the botanists in Gibraltar. 



In the ' Synopsis of Plants' are enumerated 456 

 species of flowering plants and ferns indigenous to 

 Gibraltar, and 44 species whieh are cultivated or 

 introduced. As far as the extent of my enquiry has 

 enabled me to judge, the 456 species indigenous to 

 the rock, may be classed under the following heads : 

 40 species generally distributed through Europe. 



58 natives of the south of Europe. 



63 common to Europe and Africa. 



1 74 common to the south of Europe and 



Africa. 



13 confined to Spain and Barbary. 



96 common to Europe, Asia Minor, 



and North of Africa. 



1 2 confined to Europe and Asia Minor. 



Among these are 140 species common to Great Bri- 

 tain ; 170 species are found to grow in Madeira 



