STERNA REGIA, ROYAL TERN. 669 



is especially remarkable for its great cojiiparative depth at the base, the width at the 

 base beiug uo greater than that of the skins from Europe. This gives to the bill quite 

 a different shape. The next most striking discrepancy is fonnd in the length of the 

 wing from the carpal joint, in which dimension the American bird surpasses the Europ- 

 ean by fully 1^ inches. The greatest variation I have fonnd in specimens from the 

 same continent is only about l an inch. Indeed the wing of the adult European hardly 

 exceeds that of a young American bird of the year. But there are uo other discrepan- 

 ancies, and as it is probable that a larger suite of skins than that examined would 

 show a wider range of individual variation, it may not be necessary to recognize 

 var. imperator. 



STERNA (THALASSEUS) REGIA, Gamb. 

 Royal Tern, 



(?) Grande Hirondelle de mer de Cayenne, Buff., viii, 346; whence Sterna maxima, Bodd., P. 

 E. 988 ; S. cayeitnensis, Gm., Syst. Nat. i, 1788, 604 ; Cayenne Tern, Lath., Syn. 

 vi, 352 ; S. cuyana, Lath., lud. Orn. ii, 1790, 804. (Doubtful.) 



Sterna maxima, Scl. & Salv., P. Z. S. 1871, 567 (Middle and South America). 



Sterna cayennensis, Leot., Ois. Trinidad, 535. 



Sterna cayana, Bp., Svn. 18-28, 3-53. — Nutt., Man. ii, 1834, 268. — Aro., Orn. Biog. iii, 183.5, 

 505 ; V, 1839, (139 ; pi. 273 ; Syn. 1839, 316 ; B. Am. vii, 1844, 76. pi. 429.— De- 

 Kay, N. Y. Fauna, ii, 1844, 299, pi. 127, f. 277.— GiH., B. L. I. 1844, 35.5. 



Thalassens cayanus, Bp., List, 1838, 61. — Gosse, B. Jam. 1847, 431. 



Sterna regia, Gamb., Pr. Phila. Acad, iv, 1848, 228.— La\vr., B. N. A. 1858, 859. — Newt., 

 ibis, i, 18.59, 371 (Santa Cruz).— Cab., J. f. 0. v, 234 (Cuba).— Buy., Pr. Bost. 

 Soc. vii, 1859, 134 (Bahamas).— Scl., P. Z. S. 1861, 82 (.Jamaica).- DiiESS.,Ihis, 

 1866, 44 (Texas).— TURNB., B. E. Pa. 1869, 47 (New Jersey).— Coites, Key, 1872, 

 319. — RiDGW., Rep. Surv. 40th parallel (in press ; Nevada, breeding). — Ridgw., 

 Ann. Lye. N. Y. x, 1874, 391 (Illinois). 



Thalas8eu8 reqivs, Gamb., Journ. Phila. Acad, i, 2d series, 1849, 228.— Coues, Pr. Phila. 

 Acad. 1862, 539.— Coues, Ibis, 1864, 388 (Guatemala).— Salv., Ibis, 1866, 199 

 (Guatemala). — Lawr., Ann. Lye. N. Y. viii, 1864, 104 (Sombrero); viii, 1866, 

 299 (New York) ; ix, 1868, 210 (Yucatan).— Gundl., Repert. 1866, 392 (Cuba).— 

 Coues, Pr. Bost. Soc. xii, 1868, 126 (South Carolina).— Coues, Pr. Phila. Acad. 

 1871, 42 (North Carolina ; biography). 



Phatusa regia, Bp., Compt. Rend. 1856, 772. 



{^) " Sterna crythrorbynchus, Maxlm,, Beit, iv, 857. — TsCHUDi, F. N. Peru. Jrrs, 305. — 

 BuRM., Syst. libers, iii, 450" (Sex. & Salv.). 



"Sterna (jahriviiluta, Pelz., Orn. Bras." (error for this species, sec. Scl. & Salv., 

 P. Z. S. 1871, .565). 



(^1) Sterna ehloripoda, Vieill., Nouv. Diet, xxxii, 171 ; E. M. 349 {Hate cogote obscuro, 

 Az., Apunt. iii, 372). (Very uncertain.) 



Hab. — More southern portions of the Atlantic coast ; north to Lotig Island. Gulf of 

 Mexico. On the Pacific side north to California. Nevada, breeding (IHdyiray). South- 

 ward into the Antilles and Central America.* South America to Brazil and Peru. 



Adult, spring phnnnfiv. — Bill about as long as that of T. easpiita, but of very ditterent 

 shape, being mucli slenderer, its height at base being only from a fourfh to a tifth of its 

 total length. Culmen gradually declinato-convex from base to tip, the amount of curv- 

 ature increasing but slightly toward the apex, which is not very acute. Commissure 

 somewliat sinuate basaliy, regularly decliuato-convex for the rest of its length. Rami 

 decidedly a little concave along tiieir edges. Gonvs straight, shorter than tlic rami, 

 the prominence between the two illy developed. Wings of ordinary lengtii, the ])rima- 

 ries of the usual shape and relative leugtlis. Tlie tibia' are bare for a considerable 

 distance (0.90 of an inch). The tarsus is not longer than the middle toe aiul claw. Ita 

 anterior aspect .shows a tendency toward reticulations instead of transverse scutella, 

 but there are usually some scales which extend (piite across it. The lateral and poste- 

 rior aspects are thickly reticuhited, as in vaspius, but the plates are iu)t ,so rough nor 

 elevated. The toes have tlic usual relative length for this gj-nus. Tiie iuterdigital 

 membranes are as described mider casjiiiis, but the emargin.-itiou is not quite so great. 

 The tail is long for tliis genus, and ipiitc! (h('i>ly forked. Tile central feathers are 

 broad to tiieir very tips, wliieli are rounded; tlie hiteral ones grow successively nu)ro 

 elongated and narrower toward tluiir tips, the external pair being slender and quit* 

 lilamentons for some distance from their narrow rounded apices. 



* Audubon says that these birds are found in f.a1>rador. This is certainly an error; 

 and the birds that he observed there, an<l mistook for this species, must have been in- 

 dividuals of the .S. canpiuH. 



