104 EXCURSIONS IN MADEIRA 



sides of the ravines, while the slightest coating of earth on the 

 same rock presents us with a higher class of lichen, and a moss ; 

 as this earth augments, we find the semperviva and saxifragea, and 

 thus proceed, until we are shaded by thick groves of chestnuts '. 



The variety of aspect, the different quantities of moisture (either 

 owing to the constant vicinity of the clouds or the torrents), the 

 greater or less exposure to the sea-breezes, aU conspire to render 

 the division of plants into regions extremely difficult. My first 

 visit was to the eastern side of the island, where I fancied I could 

 decide on the different heights of plants, but on going to the 

 westward, there was so little accordance between the two, that I 

 can only now venture upon the greater outhnes. I have divided 

 my list into families, that a comparison may be made between 

 the proportions they bear to each other, and that the total absence 

 of others may be more immediately noticed. In doing this, it will 

 be observed, that I have mentioned several, which are as yet but 

 premised, having only been pubhshed in the monographs of dis- 

 tinguished botanists, but which will, in all probabihty, with many 

 others merely intimated, be generally known when the second 

 edition of M. de Jussieu's Genera Plantarum appears ; an event 

 which is earnestly desired by all followers of the natural system. 

 I am not in possession of any specific descriptions of cryptogamia, 

 consequently, have only been able to notice genera, with a few 

 exceptions. With these explanations, I submit the little that I 

 have done, rather than be totally idle in this respect, whilst wait- 

 ing for a passage to Africa, where my endeavours will, I hope, 

 produce more important results. See Appendix, No. I. 



I have given what may be called the first, or Vine region, a 



' Baron de Humboldt observes, that, in countries near the tropics, succulent plants 

 appear before mosses ; but I found Madeira to accord with the general rules for the 

 progress of vegetation. 



