1909] WIELAND—WILLIAMSONIAS OF MIXTECA ALTA 441 
And once more, we are compelled to hypothesize an extensive 
and far-reaching polyphyly for the angiosperms. But, none the less, 
the thought is also present that once an approach has been made 
along all the available lines of evidence, this seeming maze of possi- 
bilities may in the end be found vastly simpler than one can now 
Picture. At least we are already persuaded that the day will come 
when the true relationships and derivation of every angiospermous 
family will be worked out and satisfactorily stated with mathematical 
precision. 
EL Instiruto GEoLocico NACIONAL 
MEXICO 
