PI.ATE IV. 



HERRING GULL. 



Pages 86, 88. 



Length, 24*00 inches. Adult, back and wings pearl-gray ; end of pri- 

 maries marked with black; rest of plumage white. Young, dark gray- 

 ish, primaries and tail brownish black. 



PETRELS. 

 Length, 7-50 inches. Black, upper tail-coverts white. 



