(ix ) 
raphers:—or, in other words, that no structural detail, of whatever 
apparent value, can safely assert itself in defiance of the argument from 
general structure ; or otherwise than as elucidated by the subtle mediation 
of Habit. 
A Synopsis of the North American lichens is in preparation, but, for 
the present, necessarily laid aside. 
AMHERST, MAass., 
June, 1872. 
