-u 
/. 
years at Ontonagon was 14, and partly cloudy 5, leaving 
an average of 137 clear days for the year. The prevailing 
direction of the wind at the same station is from the 
northwest, often veering around from the west. 
The extent and ruggednesa of the Porcupines allow 
for much local variation. The above climatic data axe not 
meant to be more than general. Their character accords with 
the general mesophytic character of the vegetation in its 
larger aspects. 
THE CLIMAX FORMATIONS. 
There are two climax plant formations covering 
the ranges of the Porcupine Mountains. On the north slope 
of the first range occurs a typical hemlock: forest. This 
gradually merges into a maple forest near the top of the 
slope. From this point maple forms the climax formation 
on the ranges to the south, though scattered patches of 
hemlock: occur on the lower slopes. Any interpretation 
of the vegetation of the region must take into account 
the relation between these two formations, their relative 
position with respect to the larger physiographic features 
and the successions leading up to them. In this paper 
the hemlock climax will be considered first. 
