42 KEY TO FAMILIES.

A. Tip of the upper mundilile more or less swullen, rounded, and sharply pninted; upper parts, including wings. and smut-times the entire plunmge, dark sooty hlueliisli, smut-times irregularly lmrred; tuil always dark, the middle feathers longest. . . . Family Stereo— rurz'i'ilw: Ski'As :ind Jinan-21:5 (Fig. (i, a), p. (3.).

1)’. Upper mandible curved hut not swollen zit the end; tuil generally white, sometimes tipped with lllilcli ; the tail~feuthers usually ofubeut'. equal length. . . . Subtlunily Larinw: GULLS (Fig. 0, b), p. (57.

7//

FIG. 7. Fit}. 8.

0. Bill straight, not hooked and sharply pointed; outer tail—feathers generally longer than the middle ones. Suhfznnily Sterninw: Tums (Fig. '7), p. 743.

1). Hill thin and bliidelike, the, lower mnndilule much longer than the upper one. . . . Family Ja’ym/mpida‘: SKIMMERS (Fig. 8), p. 85.

FIG. 9.

Order III. Tubinaal‘eS-—;\LEATHHSSES, I’r:ri:ni.s, mid Frmmns. Bill lum’klike, the tip of the upper imuidihle generally mueli enlarged; nostrils opening through tubes; hind toe reduced to a mere nail, und sometimes entirely wanting. A. Size. Very large. nnstrils sepumted and on either side of the hill. . . . Family Dim/mldrlu': ALIiA'I'Iiossl-IS (Fig. .0, (1‘), p. $6. B. Size smaller, nostrils joined and plneed 011 top of the, hill. . . . Family I’rm'el/m'iiv/wz l‘i-z'rmzm, Fi'i..\i.\ks, and SHEAIHVATERS (Fig. 9, b), p. 86.