STERNA REGIA, ROYAL TERN. 669 



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

 base beiug no greater than that of the skins from Europe. This gives to the bill qnite 

 a diilfereut shape. The next most striking discrepancy is found in the length of the 

 ■B-ing from the carpal joint, in which dimension the American bird surpasses the Europ- 

 ean by fully li inches. The greatest variation I have fonnd in specimens fiom the 

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

 exceeds that of a young American bird of the year. But there are no 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) EEGIA, Gamb. 

 Royal Tern. 



(?) Grande Hirondelle de me)- de Cayenne, Bufp., viii, 346 ; whence Sterna maxima, Bodd., P. 

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

 vi, 352 ; S. caiiana, Lath., Ind. Orn. ii, 1790, 804. (Doubtful.) 



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



Sterna cayeimensis, Le6t., Ois. I'rinidad, 535. 



Stei-na cayana, Bp., Syn. 1828, 353.— Nnrr., Man. ii, 1834, 268.— Add., Orn. Biog. iii, 1835, 

 505 ; V, 1839, 639 : pi. 273 ; Syn. 1839, 316 ; B. Am. vii, 1844, 76. pi. 429.— DE- 

 Kay, N. Y. Fauna, ii, 1844, 299, pi. 127, f. 277.— GiR., B. L. I. 1844, 355. 



Thalasseus cayanus, Bp., List, 1838, 61.— GossE, B. Jam. 1847, 431. 



Sterna regia, Game., Pr. Phila. Acad, iv, 1848, 228.— Lawr., B. N. A. 1858, 859.— Newt., 

 ibis, i, 1859, 371 (Santa Cruz).— Cab., J. f. 0. v, 234 (Cuba).— Brt., Pr. Bost. 

 Soc. vii, 1859, 134 (Bahamas).— ScL., P. Z. S. 1861, 82 (.Jamaica).— Duess., Ibis, 

 1866, 44 (Texas).— TuENB., B. E. Pa. 1S69, 47 (New Jersey).— CouES, Key, 1872, 

 319. — EiDGW., Rep. Surv. 40th parallel (in press ; Nevada, breediug).— Kidgw., 

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



Thalasseus regius. Game., Jouru. Phila. Acad, i, 2d series, 1849, 228.— Codes, Pr. Phila. 

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

 (Guatemala). — Lawk., Ann. Lvc. N. Y. viii, 1864, 104 (Sombrero); viii, 1866, 

 299j;New York) ; ix, 1868, 210 (Yucatan).- Gdndl., Eepert. 1866, 392 (Cuba).— 

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

 1871, 42 (North Carolina; biography). 



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



(J) " Stei-na erythrorhynchus, Maxim., Beit, iv, 857. — Tschddi, F. N. Pern. Avr^, 305. — 

 BuHM., Syst. tJbers. iii, 450" (Scl. & Salv.). 



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

 P. Z. S. 1871, 565). 



{^^) Sterna cliloripoda, VlElLL., Nouv. Diet, xxxii, 171 ; E. M. 349(ffa(e' coyote obscuro, 

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



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

 Mexico. On the Pacific side north to California. Nevada, breeding (i?i(?</iw.i/). South- 

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



Adult, spring plumage. — Bill about as long as that of T. caspins, but of very different 

 shape, being much slenderer, its height at base being only from a fourth to a fifth of its 

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

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

 somewhat sinuate basally, regularly declinato-convex for the rest of its length. Rami 

 decidedly a little concave along their edges. Gonys straight, shorter than the rami, 

 the prominence between the two illy developed. Wings of ordinary length, the primar 

 ries of the usual shape and relative lengths. The tibiaj are bare for a considerable 

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

 anterior aspect shows a tendency toward reticulations instead of transverse scntella, 

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

 rior aspects are thickly reticulated, as in caspias, but the plates are not so rough nor 

 elevated. The toes have the usual relative length for this genus. The interdigital 

 membranes are as described under caspius, but the emargination is not quite so great. 

 The tail is long for this genus, and quite deeply forked. The central feathers are 

 broad to their very tips, which are rounded ; the lateral ones grow successively more 

 elongated and narrower toward their tips, the external pair being slender and quite 

 filamentous for some distance from their narrow rounded apices. 



* Audubon says that these birds are found in Labrador. This is certainly an error; 

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

 dividuals of the iS. caspius. 



