STERNA DOUGALLI, KOSEATE TERN. 689 



Adult, breeding plumage. — Bill aliout equal to the head, nearly as long as the tarsus, 

 middle toe and claw, together ; straight, slender, much compressed, much higher than 

 broad at the base, the tip excessively acute, culinen very narrow and transversely very 

 convex, evuu at the base ; gently and equally curved from base to tip. Commissure a 

 little sinuate toward the base, gradually declinato-convex for the rest of its length. 

 Gonys very long, much exceeding the rami, its outline very sharp, perfectly straight. 

 Outline of crura decidedly concave ; the intercrural space very narrow, two-thirds 

 filled with feathers; the eminentia symphysis very acute, but not prominent. Tomia 

 of both mandibles inflected, and, from the great compression of the bill, very closely 

 approximated for two-thirds their length. Nasal groove moderately long and wide, 

 but so exceedingly shallow as hardly to merit the name of sulais. It terminates 

 before it reaches the tomia, and a well-defined slender ridge runs forward from its an- 

 terior extremity till it is lost in the tomia. Nostrils of ordinary size and shape. 

 Encroachment of the feathers on the bill as usual. Wings considerably short for this 

 genus, a little rounded ; the first primary only moderately longer than the second ; all 

 rather obtuse, with rounded tips. Tertials and inner secondaries rather long and flow- 

 ing. Tail exceedingly long, contained scarcely 1^ times in the wing ; the central 

 feathers short and rounded at their ends ; the lateral excessively elongated, slender, 

 tapering regularly to a very acute point.* The feet are of moderate length and stout- 

 ness. The tibise are bare for only a remarkably short distance. The usual scutellation 

 and reticulation. Tarsus a little longer than the middle toe alone; a little shorter 

 than the middle toe and claw. Lateral toes short ; the outer not reaching the base of 

 the claw of the middle ; the tip of the claw of the inner falling short of the base of 

 the claw of the middle. Webs of moderate width and amount of emargination. 

 Claws rather short, and all remarkably arched and curved, moderately acute, the edge 

 of the inner a little dilated. 



Bill pure black ; its tip in cxtremo slightly yellowish ; its base for a varying distance, 

 and the inside of the mouth, bright red. Pileum pure, lustrous, velvety black ; extend- 

 ing far down on the nape and also very broad, reaching to the lower level of the eyes, 

 and widening somewhat on the temples and auriculars. Under eyelid, however, white, 

 as is also a rather broad streak which runs along the side of the upjier mandible to 

 the extremity of the feathers. Neck all round and whole under parts, including the 

 under surfaces of the wings, pure white, with a more or less notable tinge of a delicate 

 rosy color. On the back of the neck the white insensibly shades into the very light, 

 delicate pearl-blue which extends over the whole upper parts, including the rump and 

 base of the tail, where, however, it is slightly lighter than on the dorsum. The tips 

 of the tertials and the inner vanes of the secondaries fade into pure white. The shafts 

 of all the primaries are on both sides pure white nearly to their tips. The outer web 

 of the first primary is deep grayish-black, lighter at the tip. All the primaries are 

 light grayish-black, very strongly silvered over. The inner webs of all of them are 

 pure white for more than half their breadth ; this white portion being broadest on the 

 first, toward the base of which it occupies the whole web ; and on all of them contin- 

 uing quite to the apices of the feathers, and even going around the tips slightly on to 

 the onter web. The long rectrices are white, with just an appreciable shade of 

 pearly. The legs and feet bright yellowish-red ; the webs lighter, the claws black. 



Adult, winter plumage. — Bill dull black ; the tip for a greater distance dull yellowish ; 

 the base of the under mandible somewhat brownish. The forehead and cheeks white. 

 The crown of the head, the occiput, nape, auricular and circumocular regions, brown- 

 ish-black, almost or quite unmixed with white, except just on the vertex. There is, 

 therefore, a greater extent and iierraanency of the pileum than in most other species. 

 Neck all round and under parts white, without any roseate tinge. Lesser coverts along 

 the edge of the fore-arm brownish, but the band narrow and not very dark colored. 

 Something of the brownish is also to be traced along the edge of the metacarpus. Pri- 

 maries and secondaries much as in summer. The tail has, however, quite lost its length, 

 the external rectrices being so much abbreviated as to produce only oue or two inches 

 of emargination, and the tail, with its coverts, may be pearly like the back. 



Toung-of-the-year he/ore the moult. — Length 10.00 to 11 inches. The bill is exceedingly 

 smalt, slender, and weak ; its tip obtuse ; its ridges and angles poorly defined ; and it 

 is everywhere covered with skin so soft as to wrinkle in drying. It measures hardly 

 1.10 inches in length by 0.25 in height at the base (compare dimensions of adult) ; it 

 is wholly dull greenish-black, a little lighter at the base of the lower mandible. The < 

 primaries have not fully grown out, so that the wing from the carpus measures only 

 7.25; the second primary is longest, third nearly equal, first short, scarcely exceeding 

 the fourth. The primaries are colored, however, almost exactly as in the adults, as 

 regards their pattern, the broad white inner margins extending around their tips. 

 The shafts of all are pure white, except apically. 'J he outer web of the first primary 



* The external rectrices of this species are for the Stcrninm almost what the central 

 rectrices of Slercorarins Imffoni are for the Lestridinw, in comparison with other species 

 of their respective subfamilies. 



44 



