352 



The following extracts are in accordance with an opinion we have 

 frequently ventured to express, namely, that although elevation and 

 climate doubtless exercise considerable influence over the vegetation 

 of a district, yet that an influence fully as powerful is exerted by the 

 character of the soil. 



" The geological structure of the island is almost wholly volcanic, basalts and ba- 

 saltic conglomerates and other igneous rocks forming the whole mass of the island. At 

 one or two places there appear beds of tertiary limestone and other non-volcanic for- 

 mations, but in so very small a proportion to the whole surface, as to have no effect 

 upon the character of the vegetation." — p. 72. 



" The indigenous Flora is smaller than might be expected from the range of cli- 

 mate, the effect probably of the want of variety of soils, and the absence of other causes 

 of difference of vegetation. The most conspicuous natural families are, the Filices, 

 the Laurincce, the Compositse and the Labiatse. Of the Ericese, there are two plants 

 which attain to a remarkable growth in the island, — Vaccinium maderense and Erica 

 arborea. The whortleberry forms little thickets or forests on the mountain sides, often 

 from fifteen to twenty feet in height. The heath grows eveiywhere on the mountains 

 beyond 2500 or 3000 feet above the sea. On Pico Ruivo, the highest peak in the 

 island, it commences at about 3500, and covers most of the mountain side to nearly 

 the summit, which is more than 6200 feet above the sea. The stems are frequently 

 six, and sometimes eight feet in circumference.* The wood is very hard, and is used 

 for most of their common work by the peasants. The other indigenous forest trees 

 chiefly belong to the Laurineae. The Laurus indica, Vinhatigo of the natives, grows 

 to an immense size. Its wood is of a dark colour, and of excellent quality, and is em- 

 ployed in various articles of work, under the name of Madeira mahogany. Of foreign 

 trees, the most conspicuous is the chesnut, Castanea vulgaris, which was introduced 

 by the early settlers; it forms line woods on the lower parts of the mountains, espe- 

 cially in the interior, and on the north coast.'' — p. 73. 



X. On the Specific Value of the Antherine Appendages in the Genus Viola, 

 By Edward Forbes, M.W.S., Foreign Secretary of the Botanical 

 Society. 



Mr. Forbes observes that " form is the chief if not the only source 

 of specific character in the vegetable kingdom : " the higher divisions 

 are founded on modifications of the internal structure of plants, but 

 in characterizing minor groups and species, we ought rather to attend 

 to the modifications of external form. The reason for this will be 



*Sir J. E. Smith, in his ' Tour on the Continent,' says — " I never saw Erica arbo- 

 rea so truly arboreous as in this place, [between Frejus and Cannes]. It was often ten 

 feet high, with a trunk three inches in diameter, much resembling, in form and size, 

 the trees on Box-hill in Surrey. I am informed by Dr. Lind, that it grows to a much 

 larger size, even 18 inches in diameter, on the Serra at Madeira, 5165 feet above the 

 sea."— i. 210, Etl. 2. 



