12 
THE FORKED-TAILED GULL. 
Adult Male. 
Bill rather shorter than the head, nearly straight, rather slender, com- 
pressed. Upper mandible with its dorsal line straight to the middle, then 
curved and declinate, the ridge convex, the sides slightly convex, the edges 
sharp and inflected, the tip rather obtuse. Nasal groove rather long and 
narrow; nostrils in its fore part, longitudinal, sub-medial, linear, pervious. 
Lower mandible with a slight prominence at the end of the angle, which is 
long and narrow, the dorsal line then straight or slightly concave, the ridge 
convex, the "ides nearly flat. 
Head of moderate °ize. Neck short. Body rather slender. Wings very 
long. Feet of moderate length, rather strong; tibia bare below for a short 
space, covered behind with narrow scutella; tarsus compressed, anteriorly 
covered with numerous scutella and three inferior' series of transverse scales, 
laterally with rounded scales, posteriorly with oblique scutella. Toes slen- 
der, scutellate above ; first extremely small, second much shorter than 
fourth, third longest, anterior toes connected by reticulated webs, the outer 
and inner slightly marginate ; claws small, compressed, obtuse, that of 
middle toe with an expanded inner edge. 
Plumage close, soft, blended. Wings very long and pointed ; primaries 
tapering and rounded, first longest, second almost equal, the rest rapidly 
graduated; secondaries obliquely pointed, the rounded extremity extending 
beyond the tip of the shaft, which is exterior to it, the inner feathers more 
elongated. Tail of moderate length, forked, of twelve feathers. 
Bill black at the base for more than half its length, the rest pure yellow. 
Edges of eyelids vermilion, as is the inside of the mouth. Feet black. 
Head and upper part of neck all round blackish-grey, that colour terminated 
below by a ring of pure black encircling the neck. Lower neck all round, 
the whole lower surface, the upper tail-coverts and the tail, pure white. 
The back and" wings are bluish-grey, excepting a large terminal portion of 
the secondaries, and the tips of the primaries, which are white, the primaries 
themselves being black, with their shafts brownish-black. The first quill 
of the specimen figured had no white on the tip, but some individuals differ 
in this respect. 
Length to end of tail 13 inches, to end of wings 14f ; extent of wings 33; 
wing from flexure lOf ; tail 5; bill along the ridge 1, along the edges 1£; 
tarsus lfV; middle toe 1. its claw Weight 7 oz. 
The Female is rather less than the male, but in other respects similar. 
