Faune Oenithologiqüe de IiA Sibéeie Oeientale. 
1019 
aYi Manteau cendré L.argentatus v.Vegae 
aSj Manteau ardoisé foncé schistisagus. 
ad. Taille moins forte; manteau cendré bleuâtre 
ay Taille plus forte (aile 370 — 397 mm.) cams nivevs. 
a§ Taille plus petite (aile 335 — 380 mm.) caniis. 
b. Queue terminée largement de noir L. crassirostris. 
402. Larus barrovianus. 
Larus barrovianus Ridgw. The Auk. 1886, vol. III, n. 3, p. 330. — Nelson, Rep. Nat. H. Coll. 
Alasea, p. 51. 
Larus glaucus Palmén, Bidr. Sibirisk Ishafsk. Fogelf. Vega-Exped. p. 365 (partim.). 
«In plumage ressembling L. glaucus and L. leucopterus, and in size intermediate 
between these two species; very different from the former, however, in shape of the bill, 
which bas 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 glaucus with an obvions or tolerably abrupt line of démarcation between the white 
tips on the primaries and the pearl blue of their basal portion». 
«Males (four specimens): wing 17,00 — 18,00 (average 17,44); tail 7,30 7,50 
(7,45); culmen 2,00 — 2,30 (2,19); deptli 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 specimens) 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 JV?. 88,912 Ü.S. Nat Mus. S ad. Point Barrow, Alasea 
August 4, 1882; Middleton Smith collecter. 
«There is apparently no différence in plumage between the two species in the immature 
plumages, of which the National Muséum collection possesses a good sériés 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. 
403. Larus glaucescens. 
Larus glaucus Pall. Zoogr. Ross.-As. II, p. 320 (pt.). — Micld. Sibir. Reis. II, pt. II, p. 241, 
tb. XXIV, f. 3. — Radde, Reis. Süd. Ost-Sibir. II, p. 382. -Dyb. J. f. O. 1876, p. 202.— 
Taez. Bull. Soc. Zool. Fr. 1876, p. 263. — Dyb. et Taez. Bull. Soc. Zool. Fr. 1884, p. 147. 
