FAMILY LARIDiS. — GULLS AND TERNS. 43 



Outer web of outer tail feather, darker than inner web; back, pearl gray; breast 

 and uiKierpart*, pearl gray; bill, in adults, entirely red; tarsus, usually less than .70. 



Sterna paradiscea. Arctic Tern. 

 See No. 46. 



Back, l)Iack; a white stripe from forehead, extending over the eye ; breast, white; bill, 

 in adults, black. SU'rnu fuUijbwsa. Sooty Tern. 



See No. 49. 



Back, soot^- or grayish l)rown; a white stripe from forehead, not reaching above the 

 eye; bill, l)lack. Sterna anatlut us. Bridled Tern. 



See No. 50. 



Bnck, sooty brown; underparts, sooty brown. Anous stolidus. Noddy Tern. 



See No. 53. 



* Group 5. Wing, 11 to 13 inches long. 



Bill, black, not ti])ped with yellow; feet, blackish; back, pearl gray ; bill, comparatively 

 short and stout. Gelorhdkhni nilotira. QuII-billed Tern. 



See No. 39. 



Bill, black, not tipped with yellow; feet, black; back, black or sooty. 



Sterna fuligiuosa. Sooty Tern. 

 See No. 49. 



Bill, red, tipped with black; feet, orange red; back, pearl gray or gray and bulT. 



Sterna hirundo. Common Tern. Wilson's Tern. 



See No. 4i. 



Bill, black, tipped with pale yellow ; feet, dark; hill, comparatively long and slender. 



Sterna sandvicenisis acnflavida. Cabot's Tern. 

 See No. 39. 



* 



Group 6. Wing, 13 to 17 inches long. 



Bill, orange or yellowish; tarsus, less than l..")0; inner web of outer primary, usually 

 with inure nr lf<s white. Sterna maxima. Royal Tern. 



See No. 41. 



Bill, red or reddish; tarsus, over 1.50; inner wel) of outer primary, usually wiihout 

 wliite. .Sterna rasjna. Caspian Tern. 



See No. 40. 



Bill, bhick, ti|)iied with yellow. Sterna sandiu'censis arnrfarida. Cabot's Tern. 



See No. 39. 



* Group 7. Wing, over 17 inches long. 



Bill, red or rrddi-b. Sfmni <;isjiia. Caspian Tern, 



See No III. 



♦ For directions for ineaauremeut, see page 9. 



