BIRDS OF NORTH AND MIDDLE AMERICA, 467 
Range.—Cosmopolitan, in warmer regions, mostly on sea-coasts. 
(About seven species, four of them American.) 
KEY TO THE SPECIES OF THALASSEUS (ADULTS ONLY). 
a. Bill red or yellow. 
b. Larger (wing 358-393); billred. (Coasts of United States, northward regularly to 
Virginia and California; southward to Brazil and Peru; also west coast of 
Atfied in: wititer.)o.v2 ser secsnexeseuaterkeet anne Thalasseus maximus (p. 467). 
bb. Smaller (wing much less than 350). 
c. Billorange-red; gonydeal angle faranterior to nostril. (Pacific coast of America 
from California to Chile.)..................--- Thalasseus elegans (p. 472). 
cc. Bill lemon yellow; gonydeal angle very little anterior to nostril. (Atlantic 
coast of South America, from Venezuela to Patagonia.) 
Thalasseus eurygnathus (p. 474). 
aa. Bill black, usually tipped with yellowish or whitish. (Thalasseus sandvicensis.) 
b. White edging to three or four outer primaries much wider, extending quite to 
tip; wing and tail averaging decidedly longer? (Western and southern Europe 
and eastward to Caspian Sea; south in winter to Persian Gulf and Cape of 
Good Hope.)........--. Thalasseus sandvicensis sandvicensis (extralimital).¢ 
bb. White edging to three or four outer primaries much narrower, usually not 
extending to tip, which is occupied by an extension of the dark gray inner 
stripe; wing and tail averaging decidedly shorter? (Southern Atlantic and 
Gulf coasts of United States and Mexico; in winter, both coasts of Mexico 
and Central America, Bahamas, Greater Antilles, and southward to Brazil and 
Colombia.)..........-...-+---- Thalasseus sandvicensis acuflavidus (p. 476). 
THALASSEUS MAXIMUS (Boddaert). 
ROYAL TERN. 
Adults in breeding(?) plumage (sexes alike).—Entire pileum, includ- 
ing occipital crest, nape, and upper half of lores, uniform deep black; 
rest of head and neck, under parts, rump, upper tail-coverts, and 
edge of wing immaculate pure white; back, scapulars and wings pale 
@[Sterna] sandvicensis Latham, Gen. Syn., Suppl. i, 1787, 296 (Kent, etc.).—[Sterna] 
cantiaca Gmelin, Syst. Nat., i, pt. ii, 1789, 606 (near Sandwich, England; based on Sand- 
wich Tern Latham, Synop., vi, 356; etc.).—Sterna cantiaca Temminck, Man. d’Orn., 
1815, 479; Werner, Atlas, Palmipédes, 1828, pl.3; Gould, Birds Eur., v, 1837, pl. 415 and 
text; Naumann, Vég. Deutschl., x, 1840, 50, pl. 250; Schlegel, Vog. Nederl., 1854, 
611, pl. 359; Sclater and Salvin, Proc. Zool. Soc. Lond., 1871, 569, part (monogr.); 
Saunders, Proc. Zool. Soc. Lond., 1876, 653, part (monogr.); Cat. Birds Brit. Mus., 
xxv, 1896, 75, part; Dresser, Birds Europe, viii, 1877, 301, pl. 586.—Thalasseus can- 
ttacus Boie, Isis, viii, 1822, 563.—Thallasseus cantiaca Boie, Isis, viii, 1822, 880.— 
Actochelidon cantiaca Kaup, Natiirl. Syst., 1829, 31, 196; Gould, Birds Great 
Brit., v, 1873, pl. 69 and text.—Thalasseus cantianus Brehm, Naumannia, 1855, 
295.—[Sterna] boysit Latham, Index Orn., ii, 1790, 806 (new name for S. cantiaca 
Gmelin).—Sterna boysit Temminck, Cat. Syst., 1807, 184.—Sterna stubberica Otto, 
in German ed. Buffon’s Hist. Nat. Ois., xxx, 1790, 104.—(?) Sterna columbina 
Schranck, Fauna Boica, i, 1798, 282.—Sterna canescens Meyer and Wolf, Taschenb., 
ii, 1810, 458.—Thalasseus canescens Brehm, Vég. Deutschl., 1831, 776.—Thalasseus 
candicans Brehm, Vég. Deutschl., 1831, 777.—Thalasseus pauli de wurtemberg 
Brehm, Vogelf., 1855, 346 (Greece).—Sterna sandvicensis sandvicensis Baird, Brewer 
and Ridgway, Water Birds N. Am., ii, 1884, 289, footnote (ex Sterna sandvicensis 
Latham, Synop. Suppl., i, 1787, 296); American Ornithologists’ Union, Check List, 
1910, 48. 
