Vol. XIX-| KoBBE, T/ic Status of Certain Species of Lams. 21. 



igo2 J ' J Jr . J 



The color of the mantle is said to be of a lighter shade in Larus 

 argentatus than in Larus vegce. The orbital ring of Lams argen- 

 tatiis is said to be yellow, while that of Larus vegcB is orange-red. 

 Are these not very indefinite and variable characters on which to 

 base a separation of species in a genus which is known to possess 

 individuals easily influenced by external conditions giving rise to 

 many shades of color in the same bird ? 



In the series of the California Academy of Sciences the man- 

 tles of these birds show every intermediate shade from the dark- 

 est to the lightest. My birds likewise have many intermediate 

 shades which cannot be called either light argentatus or dark vegcz. 

 We cannot therefore separate the two by so variable a character 

 as the shade assumed by the mantle, and the only remaining dif- 

 ference exists in the color of the orbital rings. 



From the colors noted on freshly killed adult birds collected by 

 me during the months of December, January, March, and April, 

 1900-01, I find that the color of the orbital ring is not to be relied 

 upon, as it is seldom the same, being generally black or flesh-colored. 

 This series of birds was collected on San Francisco Bay, from 

 their arrival to their departure. During March and April, just 

 before their departure, the birds assumed their breeding dress, but 

 this circumstance does not enable one to separate the two, as the 

 color of the orbital rings does not change. The feet also remain 

 flesh-colored. 



Of the many birds shot (the colors being noted) I preserved 

 fourteen specimens and these, together with the series of the Cali- 

 fornia Academy of Sciences of about twenty adult birds, formed an 

 excellent basis for the study of variability in coloration and the 

 constancy of ascribed characters. 



The following table gives the colors as noted in the freshly 

 killed birds now in my collection. 



