48& X. GENERAL REMARKS. 



relative position or predominance) of the various orders 

 differs so widely in the different zones, that it has ap- 

 peared worth while to reprint the principal orders, under 

 a re- arrangement similar to that before given for the stages 

 of altitude ; so as to bring the dominant orders of each 

 zone uppermost in its own proper column. The lists on 

 pages 486 and 487, are restricted to 29 orders; that being 

 the number of them hitherto ascertained to be represented 

 in the superarctic zone. If such a re-arrangement of all 

 the orders should be requu'ed for any purpose, those who 

 use this work will easily make it by aid of the figures 

 previously printed in the ' climatal census ' referred to, 

 pages 365 to 367. The rule or principle is very simple, 

 as here adopted. The number of its species, ascertained 

 in the zone, determines the j)osition of the order in each 

 column. And if two or more orders include equal num- 

 bers of species, their names are continued in that series 

 or succession which will accord the nearest with their 

 succession in the collective census list for total Britain. 



The nos. prefixed to the names in the first column on 

 each page are to be regarded as a key to the reading of 

 the lists comparatively with each other. In tracing across 

 the pages from left to right, from inferagrarian to super- 

 arctic zone, some of the orders rise to higher nos. or 

 positions ; others descend to lower ; others oscillating up 

 and down. The rise to higher positions may be held to 

 indicate a tendency of the order to prevail in the colder 

 climates ; the fall to lower positions in turn indicating an 

 opposite tendency. In example, there is a gradual rise in 

 the nos. for the order 



JuncacecB, 19 18 16 13 10 7, 

 So that, from being the nineteenth order in the infer- 

 agrarian zone, it becomes the seventh order in the super- 

 arctic zone. Another example of nearly similar kind 



