2. STEKCORARIUS. 331 



Ucc. Eur. p. 80 (184L') ; HM. Rev. Crit. p. cxxxiv (1844); 



Middend. Sib. Reise, p. 241 (185.3); Schl. Vog. Nfderl. p. 589, 



pi. 337 (1854) ; id. Diet: Nedcrl. Vogek, p. 233 (18G1) ; Heuglin, 



Ibis, 1872, p. 05 (Novaya Zemlya) ; Jiickel ^- Bias. Voy. Bayerns, 



p. 355 (1891). 

 Cataractes richardsonii, Macyill. Man. Br. Om. pt. ii. p. 492 (1842). 

 Kicliardson's Skua, Yctrr. Brit. B. iii. p. 489 (1843). 

 Stereorarius ceppbus, Deyl. Orn. Eur. ii. p. 295 (1849) ; Feilden, 



apud Anderson, Zvol. 187'.), p. 8 (Prince Albert Land) ; Biittikof. 



Notes Leyden Mi/s. x. p. 106 (1888 : Liberia). 

 Le.stris spiuicauda, Hardy, Rev. et Mag. Zool. 1854, p. G57 ; Bp. C. 



R. xlii. p. 770 (1856) ; id. Consp. Av. ii. p. 210 (1857) ; Verr. 



Voy. Vinson Maday. Annexe B, p. 4 (18G4). 

 Lestris benickeuii, Brehm, Nnum. 1855, p. 294; id. Vogelf. p. 336 



(1855). 

 Lestris parasiticus, var. a. coprotberes, Bp. Consp. Av. ii. p. 209 



(1857). 

 Lestris cephus. Hart/. Orn. W.-Afr. p. 253 (1857 : Gaboon, in 



Paris Mus.) ; Borgyr. Vogelf. Norddeutschl. p. 141 (1869). 

 Lestris thuliaca, Breyer, Beise n. Island, p. 418 (1862). 

 Stercorarius spinicauda, Layard, B. S. Afr. p. 366 (1867) ; Coues, 



Pr. Pkilad. Acad, 18(!3, p. 121 & p. 135 (critical). 

 Stercorarius tephras, Mahngren, J.f. O. 1865, p. 390 (Spitsbergen). 

 Stercorarius asiaticus, Hume, Sir. F. i. p. 269 (1873 : Mekran 



Coast) ; Butler ^^ Hume, op. cit. \. p. 294 (1877) ; Hume, op. cit. 



viii. p. 115 (1879; list). 

 Stercorarius richardsoni, Coues, Pr. Philad. Acad. 1863, p. 121 & 



p. 135 (critical) ; Seehohm, Brit. B. iii. p. 353 (1885) ; id. {Bunge) 



Ibis, 1888, p. 349 (Gt. Liakoff Is.). 

 Lestris longicauda, Finsch, J. f. O. 1872, p. 241 ; id. op. cit. 1874, 



p. 203 (N. Zealand). 



Adult in breeding-plumage. — Pale-hreasfed form. Feathers at the 

 base of the bill dull white ; forehead and lores ash-brown, crown 

 and occiput darker brown ; hind neck duU white, shading into ash- 

 browu on the shoulders and thicklj^ streaked with golden straw- 

 colour ; mantle, wings, tail-coverts, and rectrices darker brown, the 

 secondaries blackish, the shafts of the principal primaries white ; 

 under tail-coverts, abdomen, and under wing ash-brown ; breast and 

 chin duU white ; throat and sides of the neck whitish, streaked with 

 straw-yellow : bill brownish horn-colour, darker in front of the 

 cere; tarsi and toes black. — Darl- form. Similar, but washed with 

 sooty throughout, the underparts being nearly as dark as the mantle, 

 which is of a deeper tone than in the pale-breasted form ; the 

 acuminate feathers of the neck yellow, but not so strongly con- 

 trasted : bill rather blacker. Total length 20 inches: culmen 1'5 ; 

 wing 13; tail 5 without the central pair, which arc often 3 in. 

 longer, making a total of 8 ; tarsus l-7'5, middle toe with claw 1-7. 



The sexes are alike externally. 



The dark-breasted form is rare to the northwards of lat. 70°, beyond 

 which the white-breasted is the representative form ; but southward 

 both races are found. The colour has no relation to sex, and dark 

 and light birds are constantly to be found paired. The offspring of 

 this union is, when aduK, intermediate in character, having a duskv 



