x.\ 



INTRODUCTORY. 



counties of Sutherland and Caithness which really belonged to the 

 Moray Basin; and these jnst-mentioned excuses may perhaps be 

 more effectual and justifiable than those mentioned at the end of 

 the Preface written in 1895. In further justification, I may add 

 that the introductory chapters occupy some 150 pages of close- 

 written letter-press, and a slightly new departure has been introduced 

 in a more detailed definition of the " faunal position," which replaces, 

 or at least supplements, the former chapters upon "geographical 

 position." This is only a natural result, arising from a better appre- 

 ciation of the importance of " natural boundaries," and from a natural 

 evolution in deduction from past facts ; and to place on firmer ground 

 the future amassing of facts. 



Another feature also we introduced by giving in an appendix a 

 summary of faunal values of the distribution of species in minor 

 districts within the area. (I may say that this has been worked out 

 for every area, and that it need not be a difficult essay to enlarge 

 upon that, in order to institute more complete comparisons.) 



Our eighth volume (Shetland), treating of a distinctly insular 

 area, like Orkney and the Outer Hebrides, required less minute 

 treatment as to "geographical or faunal position," or importance in 

 relation to the rest of Great Britain, as is indeed almost self-evident. 

 But this is in some measure replaced by a more complete biblio- 

 graphy, as well as an indication of its position as relating to the 

 Continent. 



Perhaps the Fair Isle, lying between Orkney and Shetland, at 

 that time of writing was the least known and least surveyed bit of 

 land in Britain. This reproach may shortly be removed,^ as there is 

 likely to be a better opportunity of thorough investigation — as I 

 write — in the present year of 1905; our indefatigable worker, Mr. 

 Eagle Clarke, already preparing to invade its precincts during the 

 autumn migration of birds there. (Chronology as at August 1905.) 

 I believe Fair Isle will prove to be yet one more ''key" to the 

 elucidation of certain migrational phenomena, as well as instructive 

 in distribution of species. 



Finally, in speaking of these past volumes, I merely make 



' Has been removed by the recordg of the results of Messrs. Eagle Clarke and 

 Kinnear's visit to the Isle in the autumn of 1905. {Aniials Scot. Nat. Hist., Jan. 

 1906. ) 



