io ANNALS OF SCOTTISH NATURAL HISTORY 



If we are to build up a satisfying structure, subjects 

 must be studied from small beginnings, and pursued to 

 bolder generalisations. Such works, we believe, as general 

 maps and treatises, built upon hypothetical foundations, or 

 imperfect data, even as regards the general subject of the 

 migration of our British birds, are premature and rashly 

 published. In some instances they are worse, being plausible 

 but decidedly erroneous, and calculated to encourage a purely 

 theoretical school at the expense of real scientific work. 

 Scientific work I hold to be simply an accumulation of facts, 

 combined with the ability to draw fairly accurate deductions 

 from them ; and in this opinion I believe I am supported 

 by a very different school of authorities from those who 

 attempt " the higher flights." 



I have said it is scarcely our province to meddle with 

 the geological aspects of the subject, yet we venture subject 

 to correction upon a few remarks. 



It is true, no doubt, that geology may and probably 

 does influence several conditions of plant and animal life ; 

 but that it does so to any such extent as to decide faunal 

 areas with permanency, beyond what may be termed 

 topographical or surface geology, or such as subsidence of 

 land or the upheaval of the same, we find it difficult to 

 realise. A great geological fault may be found to divide 

 plant- and faunal-areas from one another with considerable 

 distinctness ; and, for instance, a great range of mountain 

 limestone, growing plants and general vegetation peculiar to, 

 or characteristic of, limestone tracts, may and no doubt 

 does influence the insect and even the bird life along its 

 course ; but I find difficulty in believing that it does so 

 to an extent which would warrant the separation of faunal 

 areas by the aid of geology as regards presently existing 

 animals. Nevertheless, some useful keystones may yet be 

 placed in position by the reconciling efforts of the students 

 of these several branches of inquiry. I do not consider 

 myself competent to say more. 



The Minor Faunal Areas of Scotland are at present 

 defined either by the names of the principal river basins or 

 from their isolated positions. " Dee," " Forth," " Clyde " are 

 examples of the former, and " Outer Hebrides," " Orkney," 



