118 PROCEEDINGS OF THE 



taken as the type of another class of writers, who introduce yet 

 another useful element into their tables of distribution. He gives 

 tables of both horizontal and vertical distribution, which are 

 matters of the utmost importance, and which should never be lost 

 sight of. 



These, and many other examples of modes of registration by 

 different authors, which I might give you, do not, however, appear 

 to me to supply the desideratum of general applicahility throughout. 

 At the same time, I am inclined to consider Mr Severtzoff' s 

 divisions to be the most easily applicable to all countries, whatever 

 their physical aspects or contours may be, but with certain 

 modifications. Thus, while the four horizontal divisions of 

 Turkestan adopted by Mr Severtzoff may be most suitable to that 

 country — viz., north-west, north-east, south-west, and south-east, — 

 it might be desirable to introduce others in countries of greater 

 magnitude or different contour, or more varied physical aspects, as 

 Salvadori has done with his " Italia insidare," or, as will be seen 

 later, I have done in my treatment of the Distribution of 

 Birds in North Russia. Generally speaking, however, I am 

 inclined to adopt this method of division, and therefore I would 

 suggest : — 



1st, That the horizontal divisions of a limited area or country, 

 Zoologically-known or Zoologically-unknown, be determined by 

 their relative positions according to the compass, with such 

 additional districts as may be considered convenient, such as 

 central or insular. 



2d, That vertical divisions be determined in each country by 

 their altitudes above the sea; and that they be further individualized 

 by having appropriate names bestowed upon them, according 

 to the physical aspects peculiar to each. 



Examples. — In Norway I would, for instance, propose four 

 vertical districts (or five, if we include the adjoining fjords and 

 seas), viz. : — (1) Littoral, or sea and shore; (2) Pine tract, or sea- 

 level up to upper limit of pine growth ; (3) Birch tract, or to 

 upper limit of birch growth; (4) Fjeld tract, or Mountain tract, 

 to summits of about 8000 feet; and (5) Insular, or outlying 

 islands. But this last, in the case of Norway, is perhaps un- 

 necessary. 



Transylvania, again, I would divide as follows : — (1) Field lands, 

 or plains and valleys ; (2) Foot hills, or oak tracts, say to an 



