248 Dr. J. D. Hooker on the Vegetation 



ranthus itself, and these hardly identical with previously described plants, 

 there is no species common to the Galapagos and adjacent continent. The 

 Amaranthacece form -^ of the Phtenogamous Flora of the Galapagos, which 

 is a ten-times greater proportion than the order bears to the vegetation of the 

 whole globe. 



FiLiCES. — The very variable characters of the species belonging to this 

 order and their geographical limits being very far from defined, I hesitate in 

 considering the data they afford as of equal value with those obtained from 

 the Phsenogamic Flora. The number found in the Galapagos, 28, is certainly 

 small, considering how numerous they are on Cocos Island, a very few 

 degrees to the north, and on Juan Fernandez to the south. Their scarcity, 

 together with the absence of any Tree-fern, is no doubt due to the dryness of 

 the land and atmosphere, though the upper regions, where an epiphytical 

 orchideous plant flourishes, are to all appearance sufficiently humid for their 

 wants. Judging from botanical grounds of the humidity of a climate, we 

 must be guided by the prevalence of Ferns or their scarcity ; and when the 

 nature of the species belonging to this order is considered, it will be found 

 that many of the Galapageian species are common to drier parts of and arid 

 places in the tropics, such as Marginaria incana, Litobrochia pedata, Poly- 

 stichum coriaceum, Nephrodium molle and some others ; whilst the extensive 

 genera Hymenophyllum and Trichomanes are entirely wanting, together with the 

 whole order oi Lycopodlacece, including that most frequent of all tropical plants, 

 L. cemuum, L. A small proportion, equalling \ of the whole, are new ; the 

 remainder are the common plants of the West Indies and South America. 



The Galapagos are further the only tropical group of islands of any extent 

 which contain no Dlcksoniece and Cyathece, except the Cape Verds ; a further 

 evidence of the aridity of the climate. 



The remaining orders are all small and demand little notice; they may 

 however be enumerated under three heads, according to the distribution of 

 the Galapageian species they contain : — 



1. Orders, all the Galapageian species of which are common to both the 

 old and new world, are : — Menispermeoe 1 ; Cruciferce 1 ; CaryophyllecB 2 ; 

 Sapindacece 1 ; Zygophylleoe 1 ; Rhizophorece 1 ; Sccevolece 1 ; Plumbaginece 1 ; 

 Commelinece 1. 



