Order II
Longipennes. - JAEGERS, GULLS, and TERNS.
Birds with sharply pointed and frequently hooked or hawklike bills; toes four (except in one genus-Rissa), the front ones webbed; wings long and pointed. b FIG 6. 2/3 KEY TO FAMILIES.
A. Tip of the upper mandible more or less swollen, rounded, and sharply pointed; upper parts, including wings, and sometimes the entire plumage, dark sooty blackish, sometimes irregularly barred; tail always dark, the middle feathers longest. Family Stercorariidæ: SKUAS and JAEGERS (Fig. 6, a), p. 65. ...
B. Upper mandible curved but not swollen at the end; tail generally white, sometimes tipped with black; the tail-feathers usually of about equal length.
Subfamily Larinæ: GULLS (Fig. 6, b), p. 67. ... 23 112 FIG. 7.
FIG. 8.
C. Bill straight, not hooked and sharply pointed; outer tail-feathers generally longer than the middle ones. Subfamily Sternina: TERNS (Fig. 7), p. 76.
D. Bill thin and bladelike, the lower mandible much longer than the Family Rynchopida: SKIMMERS (Fig. 8), p. 85. upper one. ... 13 3 a a 113 b FIG. 9.