E. LÖNNBERG, HYBRID GULLS. 7 



white margin, if there has been any, is worn off. On the 

 tliird priraary the black inside the white tip extends on the 

 outer web to about 13 cm, and on the inner about 7 cm from 

 the tip. There is no mirror but only a whitish border-Iine 

 between the grey and the black on the inner web. On the 

 fourth primary the black reaches on the outer web along 

 the shaft 6 cm from the white tip, but is continued a little 

 further along the edge, the basal grey thus forms a wedge. 

 On the inner web the extension of the black is about 38 mm, 

 and it is bordered proximally by a white spöt. On the fifth 

 primary the black has the shape of a transverse, black band 

 about 14 mm in breadth, but is externally continued about 

 12 mm further proximally as a black edge. This black band 

 is bordered proximally by a white spöt on both webs, and 

 distally by the usual white tip. The following quills are 

 bluish grey with broad white ends, but without black. 



This pattern differs evidently from that of the younger 

 hybrids described above, but is more similar to the following, 

 at the same time as it also resembles in a rather remarkable 

 degree the corresponding one of Larus argentatus. 



The pattern of the primaries of a still living hybrid was 

 when examined in Sept. 1918 as follows. The first primary 

 has a 63 mm long white tip. It is thus like the first primary 

 of the specimen received 22/7 1918, except for the missing 

 small, black extreme tip. The four following primaries have 

 all white tips, bordered proximally by a subapical black band, 

 which at the shaft measures in the second primary 30 mm, 

 in the third 21 mm, in the fourth 19 mm, and in the fifth 

 7 mm, but has a broader extension towards both edges. 

 Inside this black band there is a white spöt measuring about 

 17, 12, 10 and 10 mm resp. Then follows the grey on the 

 inner web. The remaining primaries and the secondaries are 

 grey like the back with white tips. ^ 



These descriptive notes indicate that the pattern of the 

 primaries of the L. fuscus X L. leucopterus hybrids is sub- 

 jected to a certain variation with regard to the extension of 

 black and white. It is especially noteworthy that the white 

 on the end of the first and second primaries is so differently 

 developed in different hybrid specimens. This stånds, how- 

 ever, undoubtedly in connection with the fact that even in 

 the parental form L. fuscus the amount of white on the first 



