INTRODUCTORY REMARKS. 



the progress of our knowledge on the subject of geographical 

 distribution is mainly dependent on the collecting of accurate local 

 data, few will dispute; and when the field of research (however 

 small) from which those data have been gleaned constitutes an entire 

 country, circumscribed by physical barriers, and is not merely a 

 portion of some larger one, its fauna will gather in significance. On 

 this account it is that, for a certain class of naturalists, islands possess 

 a charm which is peculiarly their own, each one being in itself a 

 kind of separate, miniature world, in which we may wander at large, 

 observe, and speculate. Not that the " speculations " to which I 

 would allude will often be worth much ; but, constituted as we are, 

 it is next to impossible not to indulge in them, and they certainly 

 have the advantage of riveting our interest on these oceanic centres 

 of creation ; whilst the facts on which they rely, if carefully and 

 honestly recorded, cannot but prove of real value, sooner or later, in 

 the solution of some of the many intricate questions arising out of 

 the diffusion of animals and plants. 



The particular islands which have furnished the material for this 

 Memoir, being many in number, would seem to have many corre- 

 sponding points of interest some of which suggest themselves almost 

 intuitively. Such, for example, are their several degrees of similarity 

 inter se, and dissimilarity, as evinced by the distribution of the species 

 here enumerated; and not merely the relation (thus far) of the islands 

 to each other in the three separate Groups, but also (which is much 

 more important) of the Groups themselves. Then, again, there is 

 the resemblance, or otherwise, of their entire fauna to that of southern 

 Europe and northern Africa ; also the proportion which appears to 

 exist of endemic creatures (or those which there is the strongest 

 reason for believing are confined exclusively to the islands) ; and, to 

 what families these latter more especially pertain, a question of 

 eminent significance, when their modes of life are taken into account, 

 as bearing on the primitive conditions of the various districts which 



