GEN. 281-291 oF KEY. 
550. LARUS EBURNEUS Gm. 
Evory Guill. 
551. LARUS BEHLCHERI Vicors. 
W hite-headed Gull 
552. LARUS TRIDACTYLUS L. 
Kittiwake Guill. 
552a. LARUS TRIDACTYLUS L., 
var. KOTZEBUI (Bp.) Coues. 
Pacific Mittiwake. 
553. LARUS BREVIROSTRIS (Branpr) Covss. 
Short-billed Kittiwake. 
554. LARUS ATRICILLA L. 
Laughing Gull. 
555. LARUS FRANKLINI Rica. 
Branklin’s Bosy Guill. 
556. LARUS PHILADELPHIA (Orp) Cougs. 
Bonrnaparte’s Gull. 
557. RHODOSTETHIA ROSEA (Maccit.) Bp. 
Wedge-tailed Gull. 
558. XEMA SABINET (Sas.) Br. 
Fork-tailed Gull. 
559. XEMA FURCATUM (NeExovx). 
Swallow-tailed Guill. 
560. STERNA ANGLICA Montacu. 
Guli-billed Werm; Marsh Hern. 
561. STERNA CASPTA Patuas, 
var. IMPERATOR Coues. 
Caspian Tern. 
562. STERNA REGIA GameBet. 
Royal Wernm. 
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