Faune Ornithologique de la Sibérie Orientale. 



1019 



ay x Manteau cendré 



aSj Manteau ardoisé foncé 



L.argentatus v.Vegae 

 L. schistisagus. 



ad. Taille moins forte; manteau cendré bleuâtre 

 ay Taille plus forte (aile 370 — 397 mm.) • ■ 

 aS Taille plus petite (aile 335 — 380 mm.) ■ 



L. canus niveus. 



L. canus. 



L. crassirostris. 



b. Queue terminée largement de noir 



402. Larus barrovianus. 



Larus barrovianus Ridgw. The Auk. 1886, vol. III, n. 3, p. 330. — Nelson, Rep. Nat. H. Coll. 

 Alasca, p. 51. 



Larus glaucus Palmén, Bidr. Sibirisk Ishafsk. Fogelf. Vega-Exped. p. 305 (partim.). 



«In plumage ressembling L. glaucus and L. leucopterus, and in size intermediate 

 between thèse two species; very différent from the former, however, in shape of the bill, 

 which has the dept through the angle never less, and usually decidedly greater, than 

 through the base, instead of exactly the reverse; mantle averaging somewhat darker than 

 in 0 glaucus with an obvious or tolerably abrupt line of démarcation between the white 

 tips on the primaries and the pearl blue of their basai portion». 



«Maies (four spécimens): wing 17,00 — 18,00 (average 17,44); tail 7,30—7,50 

 (7,45); culmen 2,00—2,30 (2,19); depth of bill through angle 0,80 — 0,85 (0,82); through 

 base 0,75—0,80 (0,79); tarsus 2,55 — 2,78(2,64); middle toe with claw 2,53—2,75(2,64). 



«Females (four spécimens) wing 16,25—17,25 (16,81); tail 7,00—7,20 (7,11); 

 culmen 1,88—2,05 (1,98); depth of bill through angle 0,72—0,80 (0,75); through 

 base 0,70—0,75 (0,72); tarsus 2,40—2,50 (2,45); middle toe with claw 2,35—2,50 (2,42) 



«Habitat. Behring Sea and contigous waters, northeastward to Point Barrow, south- 

 westward to Japan (in winter). Type № 88,912 U.S. Nat Mus. cf ad. Point Barrow, Alasca 

 August 4, 1882; Middleton Smith collector. 



«There is apparently no différence in plumage between the two species in the immature 

 plumages, of which the National Museum collection possesses a good séries in ail stages; 

 but they may be very readily distinguished by the size and shape of the bill as pointed 

 out above». 



Ne connaissant pas l'oiseau des mers de Behring nous nous bornons à citer la récente 

 description de M. Ridgway, qui a comparé une riche série des oiseaux de l'Alasca et des 

 mers voisines avec une série également nombreuse des différentes localités du nord de 

 l'Atlantique. 



Larus glaucus Pall. Zoogr. Ross.-As. II, p. 320 (pt.). — Midd. Sibir. Reis. II, pt. II, p. 241, 

 tb. XXIV, f. 3. — Radde, Reis. Süd. Ost-Sibir. II, p. 382. — Dyb. J. f. 0. 1876, p. 202.— 

 Tacz. Bull. Soc. Zool. Fr. 1876, p. 263. — Dyb. et Tacz. Bull. Soc. Zool. Fr. 1884, p. 147. 



403. Larus glaucescens. 



