STEENA ANGLICA, GULL-BILLED TERN. 665 



ably developed for this subfamily, and is inserted rather low down. Webs only mod- 

 erately broad, and deeply incised, especially the outer one. Claws exceedingly slender, 

 little arched, very acute, the inner edge of the middle one moderately dilated, not 

 serrated. 



Crown and long occipital crest deep glossy greenish-black. This pilenm extends on 

 each side to a level with the lower border of the eye, and leaves only a very narrow 

 line of white to run along the edge of the feathers on the sides of the upper mandible ; 

 and it grows even wider on the latero-nuchal regions behind the eyes. Neck all round, 

 and under parts, white. Mantle light pearl-blue, this color extending on the rump to 

 the tail, .and quite to the tips of the rectrices. The tail feathers indeed are deepest 

 colored at their tips, fading into nearly pure white toward their bases, on that portion 

 of each feather which is covered with the next one. The color of the mantl(! extends 

 quite to the tips of the tertials, but dilutes a little toward the apices of the seconda- 

 ries. Shafts of primaries yellowish-white. Primaries all grayish-black, deepest on the 

 outer vane of the first ; but this color is so heavily silvered as to be really much lighter 

 in appearance. All the primaries have on their inner webs a space of white, which ex- 

 tends toward their apices for a varying distance on each. On the first the white is 

 largest, purest, and extends furthest ; is distinctly defined from the black, and has hot 

 a margin of black along itsMnner border, except just at its apex. The amount of the 

 white diminishes in length and breadth with each successive primary, until on the last 

 one it is inconspicous ; still it is quite perceptible on all. The bill is black, with or 

 without a minute yellowish tip. The legs and feet are greenish-black. 



Adult, tvinter plumage. — The winter plumage of this species, as usual among Steniinw, 

 hardly differs, except in the character of the pileum. The black usually becomes re- 

 stricted chiefly to the occiput and nape, extending forward o\'er the auricular and 

 temporal regions to the eye, and sometimes almost entirely disappearing, leaving the 

 whole head pure white, except a slight dusky trace through the eye and on the auric- 

 ulars. There is the usual ante-ocular lunula. The forehead is entirely pure white ; on 

 the crown this color decreases in amount, becoming mixed with blackish-brown, and 

 on the occiput almost entirely disappears. The general tint of the upper parts is per- 

 haps rather lighter than in summer. For a while after the autumnal moult the prima- 

 ries are also rather lighter than in summer, but toward spring they become fully 

 as dark. 



Young-of-the-year. — The bill is blaoklsh-brown, lighter toward its tip, dusky yellowish 

 or dull flesh-color toward the base of the under mandible. Legs and feet dull brown- 

 ish, the claws blackish-brown. The general color of the upper parts is light pearl- blue, 

 as in the adults, extending over the whole back from the neck to the upper tail-coverts, 

 and including the median and greater coverts, and the tertials. The contin uity of this 

 color, however, is interrupted by numerous more or less distinct crescentic or hastate 

 spots of dull brownish. Each feather bears a spot toward its extremity ; its extreme 

 tip, however, being yellowish or ochraceous-white, much lighter than the ground color 

 of the upper parts. Along the edge of the fore-arm there is the ordinary band of 

 brownish-black on the least coverts. The forehead and greater part of the vertex is 

 white ; but this color is interrupted on the latter by narrow lines of black along the 

 shaft of each feather ; these lines growing larger and wider toward the occiput and 

 nape, where the white nearly disappears. An ante-ocular crescent and jiost-ocular 

 space of brownish-bla^k. The neck all round, and the whole under parts, including 

 the inner wing-coverts and upper as well as under tail-coverts, pure white. Primaries 

 Inuch as in the adults ; their shafts white. Secondaries as in the adults. The tail i« 

 less deeply forked ; the rectrices much as in the adults, but fading into pure or yellow- 

 ish-white at their tips, each having a more or less distinct hastate subterminal spot of 

 brownish. The general proportions are somewhat less than in the adult, especially as 

 regards the length of the bill and of the lateral rectrices. 



Dinwnsions. — Length, 13tol4.50inche8;»extent of wings, 33to35; bill, 1.40; the gape, 

 2 ; gonys, 0.60 ; height at base, 0.45 ; tibiae naked i inch, no feathers inserted for f 

 inch ; tarsus (average), 1.30 ; middle toe and claw, 1.10 ; hallux, with its claw, 0.40 ; 

 wing, from carpus, 11.75 to 12.25 ; tail, to end of outer feather, 5.50 | depth of emargin- 

 ation, 1.50 to 1.75 inches. "Average weight 6f oz. a voird." Female usually, but not 

 always, smaller than the male. 



The anatomical characters of the species do not present any special peculiarities, and 

 therefore it has not been deemed necessary to introduce a description of them. 



This strongly marked and well-known species requires no further description than 

 the above, TThe chief variations to which it is subject appear to be those of dimensions. 

 In the above paragraph I have given what will, J think, be found to be the average. 

 The amount of variation is well displayed in the table given by Audubon. Most authors 

 assert that the female is the smaller ; but although this seems usually to be the case, it 

 does not always hold. The amount of emargination of the tail in adult birds seems 

 to be pretty constant, being, comparatively, free from both accidental or stxual variation. 

 The comparisons I have made of S. anglica with S. " aratieu " have convinced me that 

 there is not the slightest grounds on which to found a species distinct from the Europ- 



