PREFACE 
The following map and notes are based upon field notes 
made by the writer during the years 1929-1931, while in 
northwest Mexico, under the auspices of the University of 
California Department of Geography. In 1934 and 1935, 
the Border regions of Baja California, Sonora, and Chi¬ 
huahua were revisited. What ever of accuracy and of value 
there may be in these notes is derived from the instruction 
in plant geography by Professor William A. Setchell, and in 
field methods by Professor Carl O. Sauer. All available 
literature has been checked to verify and amplify the field 
notes. At the moment, this paper constitutes the most com¬ 
plete summary of the literature and knowledge concerning 
the vegetation of the area involved. It is hoped to follow 
this paper, at some time in the future, with a monograph on 
the climates of northwest Mexico, which will help in the 
interpretation of areal distributions of associations and 
formations. 
INSTITUTE ‘M Mlir 
ADQ. 
43563 
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