150 BIRDS. 



2. LARUS, Linnaeus. Gulls. 



* Primaries without any black. 



1. L. glaucus, Brtinn. Glaucous Gull. Ice Gull. 

 BuRGOMASTEK. Bill yellow with red spot on lower 

 mandible; large; L. 30; W. 18. Arctic regions; S. in 

 winter. 



• 2. L. leucopterus, Faber. White -Winged Gull. 

 Similar but smaller; L. 23; W. 17. Same region. 



** Primaries crossed with black (adult), or all black (young). 



3. L. marinus, L. Great Black -Backed Gull. 

 Coffix-Carrier. Saddle-Back. Mantle blackish slate 

 color; largest of our Gulls; L. 30 or more; W. 18; feet 

 flesh colored. N. Atlantic, S. in winter. 



4. L argentatus, Brunn. Herring Gull. Common 

 Gull. Mantle grayish blue; large, 22 to 27 ; W. ]8 or 

 less; feet flesh colored. N. Am., abundant. 



5. L. delawarensis, Ord. Ring-Billed Gull. Plum- 

 age like preceding; feet olivaceous; webs yellow; bill 

 yellowish, a black band at the tip; size moderate; L. 

 20; W. 15. N. Am., abundant. 



3. RISSA, Leach. Kittiwakes. 



1. R. tridactyla, (L.) Bon. Kittiavake Gull. Mantle 

 dark grayish blue; hind claw a minute knob; L. IG to 

 18; W. 12. Northern, U. S. in winter. 



3. GAVIA, Boie. Ivory Gulls. 



1. G. alba, (Gunner.) Ivory Gulls. Adults pure 

 white; young spotted ; L. IG to 20; W. 12. Northern, 

 rarely to U. S. in winter. 



5. CHRCECOCEPHALUS, Eyton. Rosy Gulls. 

 1. C. atricilla, (L.) Lawr. Black -Headed or Laugh- 

 ing Gull. Tarsus ^ longer than middle toe and claw; 



