JAN., 1909. BIRDS OF ILLINOIS AND WISCONSIN CORY. 25 



In brown plumages, the axillars (feathers extending from armpit) 

 are heavily barred, brown and white; in other plumages, the axillars 

 and under wing coverts are sooty brown or dark slaty brown. 



Family STERCORARIID^. Skuas and Jaegers. 



See page 41. 





Nostrils, separate, not tubular; bill, without cere; hind toe, some- 

 times very small; upper mandible, curved; unguis (end of bill), 

 not swollen; middle tail feathers, about equal in length to the others; 

 tail, rarely dark, although sometimes tipped with black or brown; 

 axillars and under wing coverts, white or gray, sometimes with narrow 

 gray lines or faint wavy bars. 



Family LARID^E. Subfamily LARIN^. Gulls. 



See page 42. 



Nostrils, separate, not tubular; hind toe, sometimes very small; 

 upper mandible, nearly straight, not hooked or decidedly rounded near 

 tip; outer tail feathers, usually longer than middle feathers. 



Family LARID^E. Subfamily STERNIN^E. Terns. 



See page 42. 



Bill, long and narrow, having tooth-like serrations on edges; 

 toes, four, the front ones, full webbed; hind toe, with flap. 



Family ANATID^. Subfamily MERGING. Mergansers. 



See pages 54,^5 6 - 



Top of bill of Merganser. 



Side of bill. 



