474 MM. P. Barker-Webb et Sabin Berthelot, 



nent a la masse des plantes dominantes, l'archipel des Canaries 

 merite bien le titre de Region boianique." 



In very many instances do these islands present most interesting 

 subjects for the researches of the botanist and vegetable physiolo- 

 gist. The mixture of species from a temperate clime with those of 

 the tropics, as mentioned in our quotation, is important, but every 

 island in the group presents something curious in the general as- 

 pect of its vegetation; each may be said to possess a miniature Flora 

 of its own; and there are in all, species, which are either peculiar, or 

 are remarkable for their abundance in only one or two stations ; 

 while the more that an advance is made towards the centre of the 

 Archipelago, the richer does the Flora become in Canarian species. 



The western group of these islands differs very markedly from 

 the eastern, and possesses some species quite exclusively. A new 

 species of a Cape genus, Manulea Canariensis, w. and b., is esta- 

 blished in the ancient crater of Bandama, and Commelina Canarien- 

 sisis only found on the banks of the rivulets around Cuidad and Ter- 

 ror. At Palma, the Umbilicus Heylandii, w. and b., is found only 

 in the pine woods of Barlavento. The Sempervivum Goochice, w. and 

 B., grows only in the ravines of the eastern coast, while the Belhen- 

 courtia Palmencis is almost concealed in the immense depths of the 

 Caldera. The existence of these plants, and of many others in so- 

 litary stations, seems quite inexplicable, and appears to be much in- 

 fluenced by local circumstances of soil and atmosphere. " Leslois de 

 la repartition des germes sur la surface du globe, peuvent seul don- 

 ner l'explication de ces bizarres anomalies : Mais ces lois se lient, 

 aux causes premieres par lesquelles la nature agit secretement ; ce 

 sont de principes qu'elle ne nous a pas reveles, et de long-temps, 

 peut-etre, nous ne pourrons pas plus penetrer le mystere de ces crea- 

 tions spontanees que celui de leur stabilite ou de leur migration." 



The littoral aspect of TenerifFe, as well as that of Canaria, Palma, 

 Gomera, and the " isle de Fer," present as it were a bulwark of 

 cliffs. The plantsin these districts take root in the chinks, clothing the 

 slopes and flats that surmount them. They are for the most part 

 species with fleshy leaves, which imbibe the vapours of the atmo- 

 sphere, or the exhalations from the sea-breeze. They belong to the 

 Ficoidece, Ckenopodece, Euphorbias, Crassulacece, &c, and though 

 these sometimes overrun the slopes of the valleys, and the sides of 

 the ravines, they cannot exist far from the influence of the sea. On 

 a little higher range we have another tribe of succulent plants, Sem- 

 pervivce, but which are not so dependent on the same circumstan- 

 ces of exposure. They are a numerous class, and grow on old walls 

 or mural precipices, where the moisture, though abundant, does 

 not lodge or remain long at a time. Rising above these cliffs the 



