154 



CHRGECOCEPHALUS PHILADELPHIA, Lawr. Bonaparte's GulL 

 Spring and fall. Not common. Often seen about our 

 rivers and lakes, and can hardly be considered as acci- 

 dental. 



A specimen in immature plumage shot Aug. 10, 1858 is 

 remarkable for the shortness and slenderness of its bill even 

 when compared with other specimens shot at the same season, 

 but as in other species of gulls the bill is a long time in 

 reaching its full length, this may be due merely to age. In 

 this specimen the head and neck are white with a broad 

 patch of grayish slate on the upper and posterior part of the 

 head and a roundish spot of slate below and posterior to each 

 eye. This spot is formed by the dark tips of the auriculars. 

 The back and greater wing coverts are light grayish blue, but 

 this color is nearly concealed on the back between the 

 shoulders and on the scapulars by the brownish tips of the 

 feathers, each of these being edged and broadly tipped with 

 yellowish white and below this with brown ; some of the 

 lesser coverts are of the same color, but those near the bend 

 of the wing are dark slate. 



The primaries are all tipped with black for about an inch 

 and this color extends along the whole length of the outer 

 and part of the inner webs of the two first primaries, and 

 along the greater part of the outer web of the third; the 

 other primaries, with the extreme tips of all except the two 

 first, are light bluish gray ; the rump, tail coverts, and greater 

 part of the tail, pure white ; the tail is crossed at the end by 

 a band of black three-fourths of an inch wide, the extreme 

 tips of the tail feathers being white. All the under parts 

 pure white, except the sides of the breast where, there is a 

 patch of very light brown ; bill light brown at the base, 

 darker at the end ; legs and feet very light yellow without 

 any tinge of the orange-red seen in those of the adult. The 

 bill is slender, slightly curved at the end, and without the 

 notch seen in that of the mature bird. 



