2 ARKIV FÖR ZOOLOGI BAND 12. NiO 7. 



in July 1916 in summer plumage. In addition to this the 

 tip of the left wing of a hybrid Gull was figured at two 

 different opportunities. 



One of the yoiing hatched in 1912 died the 19th of June 

 1913 and was presented to the Museum where it was pre- 

 served. It was a female. Another of these hybrids was 

 received the 20th of July 1918. It had then, of course, 

 attained the plumage of the fully adult bird. On these figures 

 and skins the following account is based. 



A comparison of the figure representing the hybrid in 

 its first year (Pl. I to the right) with the corresponding stage 

 of L. leucopterus proves at the first look that the former is 

 much darker. It resembles in several respects much more 

 a young L. fuscus. This is especially apparent with regard 

 to the quills of the wing. The primaries of the hybrid are 

 almost black as in L. fuscus only with a narrow light mar- 

 gin at the tip, whereas young L. leucopterus from Ivigtut, 

 Greenland, have the primaries light smoke grey (Dauthénay 

 363, 1) on the outer web and on the distal ends (the inner 

 web is more whitish) with in one specimen one, in another 

 two subterminal, somewhat darker bands inside the whitish 

 tip. The secondaries of the hybrid are intermediate in appear- 

 ance between those of the parental forms. They are dark 

 brown as in L. fuscus, but have, instead of only a terminal 

 light margin as in that one, the ends broadly mottled and 

 marmorated with whitish, whereas the same quills of the 

 young L. leucopterus are light smoky grey with a white tip 

 and a broad, subterminal white band in addition to some 

 light mottlings on the outer web, more or less extended in 

 different quills. The tail-feathers of the hybrid are more 

 similar to the dark ones of L. fuscus than to the white ones 

 with smoky grey bands and mottlings of L. leucopterus. The 

 young hybrid in its second year (Pl. 1 to the left) has as- 

 sumed a much lighter plumage. The head and neck are 

 white, streaked with smoky grey. The mantle has already 

 to some degree begun to assume a uniform colour of smoky 

 grey, but with paler edges to the feathers. The primaries 

 are blackish with narrow, white tips. The tail-feathers are 

 white at the base, becoming distally more and more banded 

 and mottled with blackish grey, which latter colour forms a 

 solid band of about 3 V2 cm at the end. 



