126 TRUDEAU'S TERN. 



arched, compressed, very slender towards the end, that of the middle 

 toe much larger, and having its inner edge somewhat dilated. 



Plumage soft, close, blended, very short on the fore part of the 

 head. Wings very long, narrow, and pointed ; primary quills tapering 

 to an obtuse point ; the first longest, the second half an inch shorter, 

 the rest rapidly graduated; secondaries short, incurved, obliquely pointed, 

 some of the inner proportionally longer and narrower. Tail of mode- 

 rate length, deeply forked, of twelve feathers, of which the middle are 

 rounded, and three inches shorter than the outer, which taper to a 

 slender point. 



Bill black, with part of the base of the lower mandible, the edges 

 of both mandibles, and their tips to the length of five-twelfths of an 

 inch, yellow. Iris brown. Feet orange-yellow ; claws dusky yellow. 

 Surrounding the eye, and extending toward the nape, is a band of 

 blackish-grey ; the fore part of the head, the lower eyelid, the cheeks, 

 and the upper part of the throat, are white. The rest of the upper and 

 lower parts are light greyish-blue, excepting the axillar feathers, the 

 lower wing-coverts, and the rump, which are white ; the tail-coverts 

 and tail are greyish-white. The primary coverts and quills are hoary, 

 but the outer five are dusky grey on the inner web, toward the mar- 

 gin, and less so along the shaft, and on the outer web ; but the shafts 

 of all the quills and tail-feathers are white, as are the inner edges of 

 the primaries and the tips of the secondaries, the inner excepted. 



Length to end of tail 16 inches ; to end of wings 15 ; bill along the 

 ridge lA, along the edge of lower mandible 2^^ ; wing from flexure 

 lO^i ; tail to end of middle feather 2f^, to end of lateral feather 5x% ; 

 tarsus lj*j ; hind toe -f-^, its claw \\ ; middle toe \%, its claw ^. 



This species has the bill more slender than Havell's Tern, and dif- 

 ferently coloured, the tarsus shorter, and the lower parts of the body 

 and neck of the same tint as the upper, whereas that species is white 

 beneath. 



It is probable that both species have the upper part of the head 

 and the nape black in summer. 



