EXPLANATION OF PLATES. 331 



Plate 17. 



Upper : Western gulls in breeding colony, Farallon Islands, August 10, 1919, a 



photograph presented by Mr. Oluf J. Helnemann. 

 Lower: Breeding colony of same, Humboldt County, California, a photograph 



presented by Mr. W. L. Dawson. 



Plate 18. 



Upper: Nest and young of western gull, Farallon Islands, July 3, 1914, a 



photograph presented by Mr. Oluf J. Heinemann. 

 Lower: Nest and eggs of same, Los Coronados Islands, Lower California, a 



photograph presented by Mr. Donald R. Dickey. 



Plate 19. 



Upper : Nesting site of herring gulls, Heron Island, Maine, July 11, 1915. 

 Lower : Herring gulls in breeding colony, Little Spoon Island, Maine, July 12, 

 1915. 



Plate 20. 



Upper : Nest and eggs of herring gull, Seal Island, Nova Scotia, July 4, 1904. 

 Lower : Another nest of same, Heron Island, Maine, July 11, 1915. 



Plate 21. 



Upper: Nest and young of herring gull, Heron Island, Maine, July 11, 1915. 

 Lower : Young herring gull, half fledged, Matinicus Bock, Maine, July, 1906 ; a 

 photograph presented by Mr. Herbert K. Job. 



Plate 22. 



Upper : Nest and eggs of Vega gull, Kolyma Delta, Siberia, July, 1916. 

 Lower: Another nest in same locality, July 6, 1917. Both from negatives taken 

 by Mr. Johan Koren for the author. 



Plate 23. 



Upper: Nesting colony of California and ring-billed gulls, Big Stick Lake, Sas- 

 katchewan, June 14, 1906, referred to on page 125. 

 Lower: Nests of California gulls, in shallow water, in same colony. 



Plate 24. 



Upper: Nest and eggs of California gull, Big Stick Lake, Saskatchewan, June 



14, 1906, referred to on page 126. 

 Lower : Nest and young of same in same colony. 



Plate 25. 



Upper: Nesting colony of ring-billed and California gulls, Big Stick Lake, Sas- 

 katchewan, June 14, 1906, referred to on page 133. 

 Lower: Nests and eggs of ring-billed gull in same colony. 



