THE BROWN-HEADED, OR MASKED GULL. 
335 
small and partially immature individuals (females chiefly) of L. ridi- 
bundus , that have borne this name •* — and whether, as this species, 
like other gulls, f differs a good deal in size, L. capistratus should 
not be reduced to a synonym of L. ridibundus , as L. argentatoides 
has been to L. argentatus. I have critically examined a number of 
specimens at various seasons, and found them to differ much in the 
relative proportions of parts ; thus, in an adult bird, only fourteen 
inches in length, shot on the 21st of January, 1835, the tarsi, &c., 
examined when fresh, were 
in. lin. 
Length (total) ... 14 0 
„ of bill above ........ 1 3 
„ „ to rictus . . . . . .20 
„ of wing from carpus . . . . . . 12 9 
„ of wings beyond tail . . . . . .26 
„ of tarsus . 1 10^ 
„ of middle toe and nail . . . . . .18 
„ of outer „ „ ...... 1 6 
„ of inner „ „ ...... 1 3f 
„ of hind „ „ ...... 0 4 
Tibia bare of feathers for 0 9 
This bird is mature : the black head is beginning to appear. Trom the upper 
portion of each black ear-spot across the nape, there is a rather faint show of black. 
Legs and bill of a colour intermediate between “ tile-red” and “scarlet-red” of 
Syme. 
Two adult birds previously noted— killed in Belfast Bay, on De- 
cember 6th, 1833 — and measured before being skinned, were 
respectively, in length, 14 and 14^ inches ; irides hazel ; tarsi and 
toes of a dull coral-red ; webs of feet chocolate-brown ; bill for rather 
more than the half from base dull coral-red, remainder (to the point) 
blackish : these birds being purchased by me and preserved, other 
characters not liable to change were left for future observation. To be 
more precise. — 
First, as to size . — The following are the dimensions of an adult 
* A specimen killed in Belfast Bay on the 22nd of August, 1844, exhibited the 
characters of the two species. It was an adult bird with pure white tail, and in the 
plumage of L. ridibundus ; but its tarsi and toes were brownish-red in colour, as 
those of L. capistratus are described to be, instead of the arterial blood-red of the 
other: the first two quills were not fully grown. Its length was 15 inches; bill 
from forehead to point, 14-| lines ; tarsus, 20 lines ; middle toe and nail, 18 lines. 
f See, under L. argentatus , my remarks on L. argentatoides. 
