INDEX TO KEY. 



Family LARID^. Gulls and Terns. 

 Subfamily LARINvE. Gulls. 



Tail, usually nearly square. 



GROUP 1. Wing, 9.50 to n inches long See page 43. 

 GROUP 2. Wing, n 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 21; bill, over 2; under parts, white See page 45. 



Section 2. Length, over 21; bill, over 2; under parts, not white " 45. 



Sections. Length, over 21; bill, under 2; under parts, white . " 46. 



Section 4. Length, over 21; bill, under 2; under parts, not white. " 46. 



Section5. Length, under 21 . ......" 46. 



GROUP 5. Wing, over 17 inches long ......" 47. 



Subfamily STERNIN^. 



Tail, usually forked. 



Terns. 



GROUP 1. 



GROUP 2. 



GROUP 3. 



GROUP 4. 



GROUP 5. 



Wing, 13 to 17 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, 9.50 to 1 1 inches long . 

 Wing, ii to 13 inches long . 



Seep. 47. 



" 48. 



" 48. 



" 48. 



" 48. 



" 49- 



" 49- 



