Contributions to Western Botany. 3 
thing but to rank as a subdivision. It is divisible into the 
Alpine and Arctic according to whether it is found on moun- 
tain tops or not. 
A peculiar feature in the life zones is the tendency to form 
tongues along streams which run far down into the lower zone, 
and other tongues on dry south slopes which run far up into the 
upper zone. These must be considered in determining the life 
zone of a species. These tongues are more extended as the 
temperature falls. All the so-called subalpine meadows are 
really alpine in origin. 
BESS. 
The use of the usual key signs is very confusing. Instead of 
these marks the writer has for years used in private a system of 
letters and will adopt this in all keys hereafter. Parts of keys 
that are co-ordinate are represented by the same letter, as A., 24°, 
3A., ete. Subordinate sections are represented by the next 
lower letter in the alphabet, combined. with the first letter such 
as AB. Subordinate sections which are co-ordinate with each 
other are represented by AB., A2B., A3B., ete. The same 
method is used with sections that are subordinate to these, ete. 
