42 



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 Stereo- 

 rariidm : Skuas and Jaegers (Fig. 6, a), p. 65. 



£. 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 Larinm : Gulls (Fig. 6, b), p. 67. 



Fio. 7. 



Fig. 8. 



0. Bill straight, not hooked and sharply pointed ; outer tail-feathers 

 generally longer than the middle ones. Subfamily Sternince : Tebks 

 (Fig. 7), p. 76. 



B. Bill thin and bladelike, the lower mandible much longer than the 

 upper one. . . . Family Bynchopidm : Skimmebs (Fig. 8), p. 85. 



Fio. 9. 



Order m. Tubinares. — Albatrosses, Petrels, and Fulmars. 



Bill hawklike, the tip of the upper mandible generally much enlarged; 

 nostrils opening through tubes; hind toe reduced to a mere nail, and 

 sometimes entirely wanting. 

 A. Size very large, nostrils separated and on either side of the bill. . . . 



Family Diomedeidm : Albatrosses (Fig. 9, o), p. 86. 

 £. Size smaller, nostrils joined and placed on top of the bill. . . . 

 Family JVocellariidce : Petrels, Fulmars, and Shearwaters (Fig. 

 9, 6), p. 86. 



