XVlll INTRODUCTOEY REMARKS. 



their fauna. Hence, for the above reasons, and in order somewhat 

 more to equalize the different portions of these widely scattered 

 Groups, we will regard the Desertas and Salvages {each, collectively) 

 as one ; in which case the following list will show the exact number 

 of species which have been observed, up to the present date, in the 

 several islands (as thus understood) of the whole archipelago*. 



Observed in Madeira proper 598 



Porto Santo 160 



Northern Deserta 22 j 



Central 77 I Desertas 87 



Southern 35 J 



Great Salvage . . 20 I ^ ^ 



2 



Great Piton 5 



Lanzarote 277 



Fuerteventura 261 



Grand Canary 341 



- Teneriffe 578 



Gomera 396 



- Palina 258 



Hierro., . 224 



It will be seen that these numbers are very much in accordai 

 with the relative sizes of the islands, and their greater or less fer- 

 tility; though doubtless they have also been regulated, in some 

 degree, by the fact of certain of them having been better explored 

 than others. And after what has already been stated on the extreme 

 difficulty of filling up the local lists of each separate island in so large 

 and scattered an assemblage, I need scarcely repeat, what I insisted 

 upon in my late Canarian Catalogue, that, although of course the 

 faunas of the different islands are to a great extent composed of species 

 which are common to them all, nevertheless, so far as the labour of 

 observation is concerned, the whole of these numbers (which amount, 

 in the aggregate to 3252) might have represented distinct species ! 

 So that when we further recollect that every unit of that number 

 corresponds to the positive assertion of some habitat-island, accu- 

 rately ascertained, and is independent of the particular localities 

 within the island (which are recorded for each, either in this or my 

 other volumes), it will be perceived that the '* 3252 " is really the 

 exponent of a vast amount of solid work. In spite of this, however, 



* Although it has seemed desirable to treat the Desertas and Salvages in the 

 collective way that I have done, nevertheless, for the sake of accuracy, I have 

 given likewise the number of the species which have been met with hitherto on 

 each of the email islands which compose them. 



