USE OI“ TIIE KEYS. 35

are brought into the same subsections, and the more variable species may be placed in several widely separated sections.

The maker of keys, however. should not try to serve two masters. If the keys will identify, they will have accomplished their purpose. The classification of our birds is shown in the body of the book, where the species are arranged according to the system adopted by the Ameri- can Ornithologists’ [‘nion.

In making these keys the birds are first assorted into several major sections or groups, according to the markings of some one part of the body. Each one of these seetions is preceded by the same kind of number or letter. The heading of a group or section applies to all the species included in it. Thus, if I does not apply to the bird you are identifying, you must, pass at once to II, or III, or IV, as the case may be. In like manner, it the bird does not [all into sections 1, A, or a, we go to 2. 11’, or b. respectively. Even should the first section describe your bird, it is well to read the sections which are contrasted with it.

As a model to show how the keys are used, let us identify, first, a male adult Red-winged Blackbird—a black bird with a red and buff shoulder-patch. Turning to the key to the family Icterz'dce, or Black- birds, Orioles. etc., we read:

“ I. \Vith yellow or orange in the under parts.

“ 11. Under parts black, with or without metallic reflections.

“ Ill. I'nder parts grayish. slate color, chestnut. or bufiy.

“ IV. Under parts black and white, or black tipped and margined with rusty."

Our bird has the under parts entirely black, so it evidently belongs in Section II. I'hder this section we read: “A. Outer tail-feather 075 or more shorter than middle ones; bill 1'00 or more in length.” Our bird has all the tail-feathers of nearly equal length, the bill less than an inch long. It can not therefore belong in A. so we go to B and read: “Outer tail—feather little if any shorter than middle ones; bill less than 1'00 in length." There is no other section, and we con— clude that our bird belongs here. Now we find a. b. r, d, each one placed directly beneath the other. and each one leading to the name of a speeies. This means that the statement following these letters refers to some mark or character by which one of these species may be known front the other. and that we should read them all. First comes “ u. Entire plumage bluish black." That will not do. Second. “ b. A red and buff shoulder-pateh." Evidently this refers to our bird. but we confirm our belief by glancing at c and (I. neither of which can apply to our speeimen; we decide. therefore. that it, is a Red—winged Blackbird. and turning to the extended description of Agelaius phw- moi-us verify our identiti 'ation.