THE VOYAGE OF H.M.S. CHALLENGER. 



In a flora of 326 species, belonging to 231 genera and 78 orders, there is a probably 

 indigenous element, consisting of 144 species, belonging to 109 genera and 50 orders. 1 

 A further analysis of this indigenous element yields the following statistics :— 



Dictyledons 

 Monocotyledons . 

 Vascular Cryptogams 



50 



109 



144 



The remarkably large proportion of orders and genera represented by the 145 probably 

 indigenous species is interesting. Similar proportions exist in most of the other islands and 

 islets whose vegetation is dealt with in this work ; indeed, a large ordinal and generic 

 diversity is a characteristic of insular floras. A parallel is offered on the eastern side of the 

 Atlantic by the flora of the Azores, where, in a total area of about 700 square miles, only 478 

 species have been collected, and these represent eighty orders, or an average of six species 

 to an order. The average for all Europe, according to Watson, 2 is seventy-four species to 

 the order; and for the British Islands, between fourteen and fifteen species. On the other 

 hand, the proportions of orders and genera to species in the flora of North America, 

 especially of Eastern, are widely different, whether we take the Northern or the Southern 

 States. Thus a rough calculation of the flora of the area covered by Gray's Manual gives 

 less than twenty species to an order. 



A glance at the general geographical distribution of the species forming the flora of the 

 Bermudas, as set forth in the following table, is sufficient to enable us to point to its 



1 The Bermudan cellular cryptogams are still imperfectly known. Including a few endemic species, the 

 following are the numbers in this work : — 



Musci . 



Hepaticse 



Lichenes 



Fungi 



Alga? 



Total 



Species. 



8 



6 



31 



24 



132 



201 



2 In Godman's Natural History of the Azores, p. 265. 



