1 844-] GALAPAGOS FLORA. 25 



Azores ; to be sure the heavy western gales would tend to 

 diffuse the same species over that group. 



I hope you will (I dare say my hope is quite superfluous) 

 attend to this general kind of affinity in isolated islands, 

 though I suppose it is more difficult to perceive this sort of 

 relation in plants, than in birds or quadrupeds, the groups of 

 which are, I fancy, rather more confined. Can St. Helena 

 be classed, though remotely, either with Africa or S. America ? 

 From some facts, which I have collected, I have been led to 

 conclude that the fauna of mountains are either remarkably 

 similar (sometimes in the presence of the same species and at 

 other times of same genera), or that they are remarkably 

 dissimilar ; and it has occurred to me that possibly part of 

 this peculiarity of the St. Helena and Galapagos floras may 

 be attributed to a great part of these two Floras being 

 mountain Floras. I fear my notes will hardly serve to dis- 

 tinguish much of the habitats of the Galapagos plants, but 

 they may in some cases ; most, if not all, of the green, leafy 

 plants come from the summits of the islands, and the thin 

 brown leafless plants come from the lower arid parts : would 

 you be so kind as to bear this remark in mind, when ex- 

 amining my collection. 



I will trouble you with only one other question. In dis- 

 cussion with Mr. Gould, I found that in most of the genera 

 of birds which range over the whole or greater part of the 

 world, the individual species have wider ranges, thus the Owl 

 is mundane, and many of the species have very wide ranges. 

 So I believe it is with land and fresh-water shells and I 

 might adduce other cases. Is it not so with Cryptogamic 

 plants ; have not most of the species wide ranges, in those 

 genera which are mundane? I do not suppose that the 

 converse holds, viz. that when a species has a wide range, 

 its genus also ranges wide. Will you so far oblige me by 

 occasionally thinking over this? It would cost me vast 

 trouble to get a list of mundane phanerogamic genera and 



