INDEX TO KEY. 



Family LARID^. Gulls and Terns. 

 Subfamily LARINiE. Gulls. 



Tail, usually nearly square. 



Group 1. Wing, g.50 to 11 inches long See page 43. 



Group 2. Wing, 11 to 13 inches long " " 44. 



Group 3. Wing, 13 to 15 inches long . " " 44. 



Group 4. Wing, 15 to 17 inches long . " " 45. 



Section 1. Length, over 2 1 ; bill, over 2; under parts, white See 

 Section 2. Length, over 2 1 ; bill, over 2; under parts, not white 

 Section 3. Length, over 2 1 ; bill, under 2 ; under parts, white 

 Section 4. Length, over 2 1 ; bill, under 2 ; under parts, not white. 

 Sections. Length, under 21 . 



Group 5. Wing, over 17 inches long 



page 45 

 45 

 " 46 

 " 46 

 " 46 

 47 



Subfamily STERNINtE. Terns. 



Tail, usually forked. 



Group 6. 

 Group 7. 



Group 1. 



Group 2. 



Group 3. 



Group 4. 



Group 5. 

 Wing, 1 3 to 1 7 inches long 

 Wing, over 1 7 inches long 



Wmg, 5.50 to 7.50 inches long 

 Wing, 7.50 to 8.50 inches long 

 Wing, 8.50 to 9.50 inches long 

 Wing, g.50 to II inches long . 

 Wing, II to 13 inches long 



42 



