{Reprinted from Ruopora, Vol. 21, No. 243, March, 1919.] 
CONTRIBUTIONS FROM THE GRAY HERBARIUM 
OF HARVARD UNIVERSITY. 
New Series.— No. LVIII. 
Litnotocica, Factors LIMITING THE RANGES oF Pinus BANKSIANA AND 
THUJA OCCIDENTALIS. 
M. L. FERNALD.. 
