COMMON TERN. 79 
neck, and all the lower parts, white, with a slight tinge of greyish- 
blue on the breast. Back, scapulars, and wings, light greyish-blue, 
the edges of the wings, the rump, and upper tail-coverts, white, slightly 
tinged with grey. First primary, with the outer web deep black, the 
shaft white, on the inner web a greyish-black band running along the 
shaft, narrow at the base, and widening so as to occupy the whole 
breadth of the web for an inch at the end, where it is hoary. The 
next five have the outer web, and a varying portion of the inner, in 
nearly their whole length hoary, but at the same time with a dusky 
Shade, which becomes more apparent at the ends; the rest of the 
quills are like the back, but margined and tipped with white. Tail- 
feathers with the inner webs white, the outer webs of the colour of the 
back, paler on the middle feathers, gradually deepening outwards, and 
on the outer feathers dark or blackish-grey. 
Length to end of tail 16 inches, to the fork of the tail 11, to end of 
wings 153, to end of claws 11}; extent of wings 31!; wing from 
' flexure 11;%; tail to end of lateral feathers 7;4, to fork 375; bare part 
of tibia 74; tarsus 73; hind toe and claw 3, middle toe and claw 1,y. 
Weight 5 oz. 
The female is similar to the male, but rather smaller. In some 
instances I have seen a small portion of the forehead white. 
Length to end of tail 15 inches, to the fork 113, to end of wings 
153, to end of elaws 11; extent of wings 301; wing from flexure 10}. 
Weight 5 oz. 
The young in their first plumage, have the bill dull greenish-black, 
with the tip yellowish ; the feet greenish-yellow. 
In winter, the bill is black, with the base pale orange, and the tip 
yellowish ; the feet orange-yellow. The colours are as in the adult, 
the forehead white, the rest of the head dusky, the upper parts 7 ll 
the feathers slightly margined with lighter. 
Length to end of tail 123, to the fork 11; to end of wings 14, to 
end of claws 103; extent of wings 29}; wing from flexure 8}. 
America and British specimens present no essential differences 
when compared in considerable numbers. The outer web of the la- 
teral tail-feather is blackish-grey, and the inner webs of the tail-feathers 
are white in all the specimens collected for comparison. The tarsus in 
American specimens varies in length from 9 to 103 twelfths, and the 
