322 KEY AXD DESCRIPTION 



* Bill not hooked ; culmen slightly but evenly curved from end to end ' 



(No. 1 is merely curved near tip -) ; tail decidedly forked (No. 1 has 

 a doubly-rounded tail ; the outer feathers are about 2 inches and 



the middle ones about ^ inch shorter than the longest ones) 



Terns, below. 



TERNS (SUBFAMILY STERNIN^) 

 Characteristics. given on |i. 321. 



Key to the Species 



* Tail doubly rounded,'' the outer feathers about 2 inches, and the middle 



ones l inch shorter than the longest ones 12. Noddy. 



* Tail decidedly forked. (A.) 



A. Tail with the outer feathers broad and rounded ; * front toes but 



little more than half webbed ; plumage dark 11. Black Tern. 



A. Tail with the outer feathers acutely pointed, and in most cases 

 narrow ; front toes well webbed ;" plumage light. (B. ) 

 B. Bill dark and stout, its depth at base over ^ the length of the cul- 



men2 1. Gull-billed Tern. 



B. Bill less stout, usually slender. (C.) 



C. Wing, 15 or more long ; tail forked for less than ^ its k-ngth 



2. Caspian Tern. 



C. Wing, 14-15; tail forked for about i its length ;3. Royal Tern. 



C. Wing less than i:] long. (D.) 



D. Head decidedly crested ; wing, 11-13 long 4. Cabot's Tern. 



D. Head but little if at all crested. (E.) 



E. Wing under 7 long ; back pearl-gray 9. Least Tern. 



E. Wing, 10:^-12 J long; back sooty-black ; inner webs of quills dusky. 



10. Sooty Tern. 



E. Wing, 8-12 long; back in adult pearl-gray. (F.) 



F. Outer tail feathers with the inner web du.sky, outer web white 



5. Forster's Tern. 



F. Outer tail feathers with both webs white 8. Roseate Tern. 



F. Outer tail feathers with inner web white, outer web dusky. (G) 

 G. Bill red with a blackened tip ; tail but little more than I the length 



of the wing 6. Common Tern. 



G. Bill red throughout ; tail over ^ the length of the wing 



7. Arctic Tern, 



