360 Synopsis of the Birds 



297. Larus kburneus, Gm. Pure white ; bill stout ; feet 

 black ; naked space above the tarsus very small ; webs some- 

 what indented ; tarsus one inch and a half; first primary 

 longest. 



Young dingy cinereous, somewhat mottled. 



Ivory Gull, Lath. Buff. pi. enl. 994. 



Inhabits the Arctic circle, whence it migrates occasionally 

 to the temperate regions of both continents. Forms another 

 transition to Sterna, by its feet and wings. 



298. Larus fuscus, L. Mantle slate black ; quills almost 

 entirely black, reaching two inches beyond the tail ; bill short, 

 not stout ; feet yellow ; tarsus two and a half inches. 



Summer plumage, head and neck pure white : winter, head 

 and neck streaked with light brown. 



Young, blackish cinereous, mottled with yellowish-rusty. 



Silvery gull, Lath. Meyer Vog. Deutsch. ii.pl. 18. 



Inhabits both continents: very common during winter near 

 Philadelphia and New- York. 



299. Larus argentatoides, Brehm. Back and wings bluish- 

 gray ; quills black at the point, tipped with white, reaching 

 but little beyond the tail ; shafts black ; first primary broadly 

 white at tip ; second with a round white spot besides ; tar- 

 sus less than two and a half inches ; nostrils oval. Length 

 twenty inches. 



Summer plumage, head and neck pure white : winter, head 

 and neck streaked with brown. 



Young, dirty mottled, varied with rusty. 



Not noticed in my Catalogue. Someivhat doubtful whether it 

 is Brehni's species. 



Inhabits both continents : common near New-York and 

 Philadelphia. We have shot it also on the southern coasts 

 of England. 



300. Larus argentatus, Brunn. Mantle bluish-gray; quills 



