aves — ■ larid^. 



General description. 



Size. — Adult male (breeding). Total length, about 15 inches. 

 Wing, 12 inches. 

 Tail, 5 inches. 

 Tarsus, 2 inches. 

 Culmen, 1.7 inches. 



Adult female birds at the same season average a little smaller. 

 Co/or. — Adult male (breeding). General color, grey above 

 white ; with a brown hood. 



Fig. 120. 



201 



bek 



Larus maculipoinis. Adult male. ^3 natural size. From material from Museo de la Plata. 



Head : With a hood of deep cinnamon brown, extending down on the 

 neck, shading into umber on the nape and throat; unbroken save by white 

 eyelids and a white patch behind the eye. 



Neck : Exclusive of hood, white. 



Back: Mantle pale bluish grey shading into almost white on the rump 

 and upper tail coverts. 



Wing: Coverts like the mantle; primaries black with white decorations 

 and markings as follows : First primary white at apical end on both sides 

 of shaft for three inches ; and black on both sides of the white shaft. Sec- 

 ond primary outer web white, and the inner web with a white area next 

 to the shaft (see Fig. 121), the larger part of this web black. The tip of 

 both webs white, a black subterminal bar crossing the feather below this 

 tip. In some individuals, presumably very old birds, this bar is confined 



