18 ARKIV FÖR ZOOLOGI. BAND 12. N:0 7. 



resp. L. leucopterus, have secondarily aquired their påle ju- 

 venile plumage with faded spöts, and that the more strongly 

 dark-spotted young of L. marinus, resp. L. fuscus, bear more 

 resemblance to the ancestors from which all Gulls once have 

 sprung.^ Thus the hybrids display in their juvenile plumage 

 a more ancestral type than the lighter of the parental species 

 do in a corresponding stage. With other words the ancestral 

 characteristic of a comparatively strongly pigmented and 

 spotted plumage is dominant, and the caenogenetio charac- 

 teristic involving a påle plumage with faded and reduced 

 spöts is recessive. Unfortunately a second hybrid generation 

 has not, as far as T know, been raised to maturity, although 

 I am told that L. marinus X L. glaucus hybrids have proved 

 fertile in the Zool. Garden of Copenhagen, laid eggs and 

 hatched them. 



With regard to the characteristics appearing in the plu- 

 mage of the mature birds it has been stated in the above 

 descriptions that the L. marinus X L. glaucus hybrids have 

 at least mostly a grey mantle, certainly darker than that 

 of L. glaucus^ but much paler than that of L. marinus. This 

 characteristic is thus to a certain degree intermediate, although 

 nearer L. glaucus. 



Concerning the pattern of the outer primaries the absence 

 of black pigment as found in L. glaucus proves to be a reces- 

 sive characteristic, and the hybrids inherit from L. marinus 

 a pattern of black with white spöts, although the black is 

 not quite so broadly developed as in the parental form. It 

 has already been mentioned in discussing the L. fuscus X 

 L. leucopterus hybrids, that a similar pattern is to be found 

 in many other species of Gulls, and that it therefore probably 

 must be understood as an at least comparatively ancestral 

 characteristic. The hybrid Gulls have thus in this respect, 

 just as was the case with the strongly spotted juvenile plu- 

 mage, inherited that kind of a wing-pattern which most 

 nearly agrees with the ancestral one out of those which are 

 represented in the parents. It is even possible that it is 

 more primitive than that of both parents. When it thus has 



^ The young Gulls recall vividly in their spotted plumage, as is well 

 known, with regard to their pattern certain vading birds as f. i. Oedi- 

 cnemus, Numenius etc. 



