36 KEY TO THE BIRDS OF EASTERN NORTH AiMERICA. 



FAMILY LARIDyG. 

 Gulls and Terns. 



SUB=FAMILY LARIN^. 

 Qulls. 



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. 



Uuderparts, while; inner web of fii'st primaiy, white, with black spot uear the eml; the 

 tip, white; shaft of feather, white; adult Inrds have tlie bill dark red; iu immature liirds 

 it is browiiisli. Lams frauklinii. Franklin's Gull. 



See Xo. 34. 



I'nderjiarts, w'hile; inner web of first primary, white; tlie tip, black; bill, black; shaft 

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



See No. 35. 



Underparts, white; inner web of lirst primary, aljout half white; shaft of feather, 

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



Xema saliiiiii. Sabine's Qull. 



See Xo. 38. 



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



Shafts (it primaries, black or dark brown; underparts, not pure white (immature). 



Larus atricilhi. Laughing Qull. 

 See No. 33. 



Uiiderpai-ts, pure wiiite; inner web of first primary, white, with black spot near the 

 end, the tip, white; sliaft of feathers, white. Adult l)irds have bill dark red; in immature 

 birds it is lirownish. L„r„s franklinii. Franklin's Qull. 



See Xo. 34. 



* For directionrt for ineaBurement, see page 9. 



