36 KEY TO THE BIRDS OF EASTERN NORTH AMERICA. 



FAMILY LARID^. 

 Gulls and Terns. 



SUB=FAMILY LARIN^. 

 Gulls. 



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 ; hind toe, small, but 

 always present except in one genus ; bill, with- 

 out cere. 



* Group 1. Wing, 9.50 to 11 inches long. 



I'liderparts, white; iiiiicr web of lirst itriinary, white, with black spot uear the eud; the 

 tip, white ; shaft of feather, white ; adult birds have the bill dark red ; iu iiiiinature l)irds 

 it is brownish. Larus fraiiklhiii. Franklin's Qull. 



See Xo. :U. 



rii(lei-i)arts, white; inner web of first i)riinary, white ; the tip, black; bill, blaek: shaft 

 of feather, white. Lams Philadelphia. Bonaparte's Gull. 



See Xo. 35. 



I'nderparts, white; inner web of firsit primary, about half white; shaft of feather, 

 dark brown on upper surface. In the adult the bill is black, tipped with yellow. 



Xema sahinii. Sabine's Qull. 



See \o. 38. 



* Group 2. Wing, 11 to 13 inches long. 



Shafts of primaries, l)lack or dark brown; underparts, not pure wliite (immature). 



Larus atricilla. Laughing Qull. 

 See Xo. 33. 



Underparts, pure white; inner web of first primary, white, with l)lack spot uear the 

 end, the tip, white; shaft of feathers, white. Adult birds have l)ill dark red; in immatun; 

 birds it is brownisli. Lams franklinii. Franklin's Qull. 



See Xo. 34. 



* For directions for measurement, see page 9. 



