APPENDIX. 421 
C.D. The Use of the Keys. 
It is impossible, so far as is known, positively to identify 
many eggs, without some knowledge of the nest and parent- 
birds. In the following “ Key to the Eggs of Massachusetts” 
(C), the position, and sometimes the structure, of the nest is 
the chief point dwelt upon; the colors of the parent-hirds be- 
ing mentioned, only when the best means of identification. 
On observing a bird for the purposes of this Key, note the gen- 
eral coloration (as in the Downy Woodpecker, black ‘and 
white), particularly above, the color of the breast, whether 
streaked (spotted) or not, the color of the crown and throat, or 
of the entire head, and the color of the tail, whether the outer 
feathers are white or not (best observed as the bird flies). 
Observe any prominent markings, and, in large hawks, the 
coloration of the tail beneath. Eggs plainly colored belong to 
§ I; eggs which are marked (not stained) to § II. In the 
former, the uniform color (as white) leads to the sections let- 
tered A, B,C. In the latter, the ground-color leads to similar 
divisions. The subsections, (a) etc., are arranged according 
to the position of the nest. Under each subsection, the list- 
numbers run continuously. Glance down the column of the next 
- figures (the extreme length and breadth of the eggs expressed 
in hundredths of an inch), until you find a size apparently 
corresponding to that of the egg in hand. If there are several 
eggs together in the Key of nearly the same size, read across 
the page until the right description is reached. You will often 
find some characteristic or means of distinction in the names 
of the birds. The figures at the end refer to the main work. 
List-numbers (to the extreme left) in parenthesis indicate rarity 
of the corresponding nest in Massachusetts, or at least rarity 
under the circumstances mentioned. >> means more than; < 
means less than. Before two numbers connected by a cross 
(X), these signs affect both. g means male; 9 means female. 
Occasionally, as is the case with the Bald Eagles, birds breed 
before attaining their full dress. 
The “ Key to the Land-birds of New England” (D) has been 
arranged as much by the coloration of birds as possible, but it 
cannot be used without having the bird in question at hand. 
On the first page, follow the lines of the table, and also the 
divisions (beginning at the right), until a reference is reached. 
. These references are to sections of the main work, unless stated 
to be to those of the Key. The former are in Arabic, the other 
in Roman, numerals. On reaching the Key-section referred to, 
find (if it is divided) the right division marked with a capital 
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