404 THE ZOOLOGIST. 



(as already stated) almost the whole value of any such scheme 

 would depend, could hardly be drawn from any more restricted 

 plan than this. Hence it was that my original intention was 

 to treat only those species inhabiting the Palsearctic region. 

 The mapping of the distribution of all known species throughout 

 the world is, of course, the ideal scheme to aim at, and the only 

 one which could be regarded as absolutely complete ; but this 

 would be such a gigantic task that no one person could be 

 expected to undertake it. 



2. Bibliography. — The first step necessary is the compilation 

 of a topographical catalogue, or bibliography, of all published 

 sources of information which treat of the geographical distribution 

 of any species in any part of the world. It would be a great 

 convenience, and would save' a large amount of space in the body 

 of the work, if the entries in this catalogue (which should 

 ultimately form an Appendix) were numbered consecutively, and 

 if reference were made to the authorities quoted, by giving first 

 the name of the authority, followed by the number appended to 

 his particular work, or article, in the Bibliography, with the 

 number of the volume (if the work consists of more than one) 

 and the page, as is done in my 'Birds of Essex' and many 

 other modern scientific works. Thus : — " It abounds throughout 

 northern Africa during winter (Gurney, 294, ii. 381)." 



The compilation of this Bibliography, though nominally the 

 first part of the work to be undertaken, would in reality be largely 

 completed (if not mainly gathered) during the progress of the 

 main portion of the work. 



3. Maps. — The second step should be the preparation of a 

 suitable uncoloured map of the world on which to indicate the 

 distribution of each species. This should, of course, be on 

 Mercator's projection. A convenient size (at least for working 

 purposes) would be " royal broadside" (20 X 25 inches). This 

 would show the British Islands about 3j inches in length, which 

 would, I think, be sufficiently large for all practical purposes. 

 The maps used in the completed work, when published, might be 

 much smaller. The map should show the main political divisions, 

 the chief towns and cities, general ocean depths, all the principal 

 rivers and mountain ranges, with perhaps a few other physical 

 details. The political divisions would be found useful when 

 entering the information on the map, as most existing mono* 



