8 ARKIV FÖR ZOOLOGI. BAND 12. N:0 7. 



and second primaries is variable. Some (old) specimens have 

 a very large, subapical white »mirror» on the first and a 

 smaller one an the second. In others, however, the white 

 spöt on the first primary may be small, and on the second 

 it is most often lacking. It is also the oldest hybrid speci- 

 mens which have most white on the first primary. 



The wing-pattern of the adult hybrids with black ends 

 to the outer primaries, white »mirrors» on the first and se- 

 cond primary etc. is as mentioned above an inheritance from 

 the father, Larus fuscus. The pigmentation of these quills 

 is, however, in the hybrid not quite similar to that of L. 

 fuscus, but has been subjected to a considerable reduction 

 and restriction to certain parts, the 5 outermost primaries, 

 no doubt by the negative influence from the mothers {len- 

 copterus) side. It is then of interest to note that by this 

 restriction of the black pigment a certain general resemblance 

 of the wing-pattern has been produced between these hybrids 

 on one side, and several other G ulls as those of the argen- 

 tatus-grou-p, canus, and the affinis-race of the fuscus-group 

 on the other side. In all these Gulls black is present on the 

 5 — 6 (7) first primaries, and decreasing gradually from the 

 first; white »mirrors» are also commonly to be seen on the 

 two first, or at least on the first. This resemblance with 

 regard to the wing-pattern in so many different Gulls cannot 

 be understood in any other way than as an inheritance from 

 common ancestors, which have had such a one. 



As this same pattern as far as the white is concerned, 

 viz. white »mirrors» on the two first primaries, and white 

 apical spöts beyond the black tips, is present to a certain 

 degree in Larus fuscus as well, it appears probable that the 

 ancestors of the latter once originally have been provided 

 with such a wing-pattern, but that this has become obscured 

 by the more intense pigmentation of the wings during the 

 course of development. The paler race, which has been 

 named Larus fuscus affinis, is then consequently the more 

 primitive or original one, and the dark, or »typical» Larus 

 fuscus represents a låter stage of evolution, which has been 

 reached by a richer and more intense development of black 

 pigment. It is thus in a certain sense a semi-melanistic 

 form. 



