CHARACTERISTICS OF GROUPS OF SILVER FIRS 69 
included in this list by authorities. A specimen sent 
me distinctly showed them. 
Branchlets and Shoots, appearance and composition 
of.—Points of difference to be noted: (1) the colour 
of the shoot ; (2) whether downy or showing here 
and there evidences of scattered pubescence, or 
without any pubescence at all—that is to say, 
glabrous ; (3) whether in composition it is corrugated 
and fissured, or whether it is smooth, or perhaps in 
some instances slightly wavy, but not fissured with 
deepened grooves, as are the representatives of the 
corrugated clique. 
This difference, as between what is corrugated and 
slightly wavy, we own reads somewhat perplexingly. 
It is far more clearly explained in the illustrations 
appended than by any mere little collection of words 
strung together by an amateur student, with best 
intent of purpose but with an acknowledged in- 
capacity to make explicit this particular point by 
use of script alone ; but if these illustrations are even 
cursorily examined with the accompanying text, they 
ought to be of assistance to the aims of any identifier. 
The difference between corrugated and smooth 
surface calls for little more strain on the powers of 
perception of ordinary man to discern than an 
opinion invited upon the difference in outward and 
superficial shape of a roof of corrugated iron and a 
covering of flat undented sheet-iron on some wayside 
farm building. 
Out of the twenty-six species of Silver Firs that 
have been called attention to, eight are corrugated, 
or if another simile be permitted, shaped more 
after the manner of wavVes in a choppy sea than the 
more gradual and gentle gradients of a ridge-and- 
furrow field in a Midland county, which would be 
more descriptive of the branchlet explained and 
portrayed as of undulate surface. 
