36 KEY TO THE BIRDS OF EASTERN NORTH AMERICA. 
FAMILY LARID/&. 
Gulls and Terns. 
SUB=FAMILY LARINA. 
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 I1 inches long. 
Underparts, white; inner web of first primary, white, with black spot near the end; the 
tip, white; shaft of feather, white; adult birds have the bill dark red; in immature birds 
it is brownish. Larus franklinii. Franklin’s Gull. 
See No. 34. 
Underparts, white; inner web of first primary, white; the tip, black 5 bill, black; shaft 
of feather, white. Larus philadelphia. Bonaparte’s Gull. 
See No. 35. 
Underparts, white; inner web of first primary, about half white; shaft of feather, 
dark brown on upper surface. In the adult the bill is black, tipped with yellow. 
Nema sabinii. Sabine’s Gull, 
See No. 38. 
* Group 2. Wing, 11 to 13 inches long. 
Shafts of primaries, black or dark brown; underparts, not pure white (immature). 
Larus atricilla. Laughing Gull. 
See No. 33. 
Underparts, pure white; inner web of first primary, white, with black spot near the 
end, the tip, white; shaft of feathers, white. Adult birds have bill dark red; in immature 
birds it is brownish. Lurus franklinii. Franklin’s Gull. 
See No. 34. 
* For directions for measurement, see page 9. 
