18 MICHIGAN BIRD LIFE. 
outermost primary and number nine or ten, as the case may be, that primary 
which is followed directly by the first secondary. When the statement is 
encountered “second or third primary longest” it must be understood that 
the actual length of the entire primary is not meant, but merely that in the 
folded or partly opened wing the tip of the second or third primary extends 
beyond the tips of any of the others. ; ; ; 
It is not practicable in this place to anticipate and explain all the difficulties 
which the beginner will experience in attempting to use the artificial keys, 
but enough has been said to enable him to make a beginning, and with 
constant reference to the figures and glossary, and especially with the exercise 
of good sense and fair judgment one should learn very quickly to use these 
keys successfully. At the risk of being tedious, it should be repeated once 
more that no measurement should ever be guessed at; the compasses and a 
measuring rule should invariably be at hand and only in the most obvious 
cases should their use be omitted. 
AN EXAMPLE OF THE USE OF THE KEYS. 
Suppose we have in hand a freshly killed specimen of one of our small fresh- 
water ducks. Starting with the Artificial Key to the Larger Groups (page 33) 
we find the first line, prefaced by a single capital A, to read, ‘Distinctly 
web-footed.—B, BB, BBB.” Examination of the bird’s foot shows that it 
is a typical swimming foot, the three front toes being connected with mem- 
brane or web. If in any doubt we should look for the alternative under the 
heading AA, which appears farther down the page and is found at a glance 
because it begins at exactly the same distance from the margin as the line A. 
But AA reads, “Imperfectly or not at all web-footed,”’ which evidently 
does not answer for our bird. So we come back to line A and consider the 
references following it, B, BB, BBB. The three lines beginning with B all 
relate to the hind toe, and as our bird has a hind toe which is not connected 
with the front toes by a web it evidently agrees with BB. This in turn is 
followed by the references E and EE, and on reading the lines so headed 
and examining our specimen we find the condition described under E, namely 
the “cutting edges of the bill with comb-like ridges.”” The reference follow- 
ing this line takes us to the Order Anseres, Ducks, Geese and Swans, where 
another key awaits us. 
The short neck, dark color and small size debar our specimen from the 
group of swans, and its comparatively short legs and long toes exclude it 
from the geese and confirm our belief that it belongs with the ducks. 
The key to the species of ducks looks somewhat formidable, but it should 
be remembered that we need only consider one or two points at atime. The 
short, broad bill, with its strainer-like plates sends us at once to AA, and then 
to decide between C and CC. Here a little investigation may be necessary, 
but a glance at the cut of the Ruddy Duck will show that it is quite unlike 
our specimen and we select CC as the right path. In order to determine 
now whether D or DD is applicable to the case in point the student should 
compare figures 15 and 21 and then carefully examine the hind toe of the 
specimen. The result points clearly to D and places this bird among the 
“River and Pond Ducks,” with the references E and EE to be considered. 
Although evidently not a very large duck, it is not safe to assume that it 
belongs under E without actual measurement. With a pair of compasses 
the exact distance from the front edge of the shoulder (in the closed wing) 
to the tip of the longest primary must be determined, and since this proves 
