G56 LAEUS PHILADELPHIA, BONAPARTe's GULL. 



DiAG. L. inter viiviimos, rosiro sternino, nigro, pediius flavis, rhacMdibus remigum prima- 

 riorum qiiinqiie alhis ajiicibus nigiis. 



Hah. — Contiuent of Nortli America, (?)Mexico aud Middle America (but no valid 

 reference seen). Casual in Europe (Great Britain). In addition to the above quota- 

 tions note : TnoMP., Ann. Majj. N. H. 1848, 192; Zool. 1849, 2069.— Leith, Zool. 1851, 

 3117 ; 1867, 966.— Yakk., Br. B. iii, 555.— PowYS, Zool. 1855, 4762.— Kkox, Zool. 1806, 

 306.— EoDD, Zool. 1865, 9501 ; fuJe Harting). 



Adult, hrecd'nig 2)Juma(ie. — Bill shorter than the head or tarsus, much compressed, very 

 slender and sternice ; both mandibles vrith a slight but distinct notch near the tip. 

 Convexity of culmen slight, gradual from base to apex. Rami slightly concave ; gonys 

 about straight. Nostrils lateral, linear, direct, pervious, extremely narrow. Tarsus 

 equal to middle toe and claw, with the ordinary scutellation and reticulation. Webs 

 moderately broad, somewhat incised. Wings and tail of ordinary characters, the latter 

 somewhat emargibate in the young. Bill black. Mouth and eyelids carmine. Legs 

 and ieet coral-icd, tinged with vermilion. Webs bright vermilion. Hood plumbeous 

 slate, not so deep as in franldini, enveloping the head and upper jiart of the neck, 

 reaching further before than behind. White patches on eyelids narrow, and half pos- 

 terior to the eye. Mantle pearl- blue, much lighter than in franldini, not so light as in 

 mimdus. Ends of the tertials and scapulars scarcely lighter than the back. Primaries : 

 shafts of the first five or six white, except at their extreme tips, the others dark col- 

 ored ; first, outer web and extreme tip black, rest white; second, white, its tip black 

 for a greater distance than the first, and on one or both webs, for a greater or less dis- 

 tance (sometimes half way down the feather) narrowly bordered with black; third, 

 fourth, fifth, sixth, black at the ends for about the same distance on each, the black 

 bordering the inner web much further than the outer ; the inner webs of the third and 

 fourth, and both webs of the fifth and sixth, of a rather lighter shade of the color of 

 the back. Other primaries like the back, the seventh and eighth with a touch of black 

 on one or both webs near the tip. The third to sixth primaries with a white or pearly- 

 white speck at extreme tip. As is not the case with either of our other species of the 

 genus, the primary wing-coverts, bastard quills, &c., are wholly or in great part white 

 (much as in cirrhocepludus or (dhijiennis of South America), which causes the whole 

 wing to be bordered with white as far as the carpus. Neck all around, and under 

 parts, including under wing-coverts, pure white ; the belly, &c., rosy in breeding time. 

 There is no difierence in color between the sexes. 



JdiiJt, ninicr plumage. — Bill light colored at base below ; feet flesh-color. Crescent 

 before the eye, and patch below the auriculars, deep slate. Crown and occiput mottled 

 with grayish-black And white. Back of neck washed over with the color of the man- 

 tle. Forehead, sides of the head and throat, white, continuous with the white of the 

 under parts. Otherwise as in summer. 



Young, first winter. — Bill dusky flesh-color, except toward the end ; legs and feet 

 light flesh-color. Without the slaty mottling of the crown. Auricular patch distinct. 

 Lesser wing-coverts and tertials dusky brown, lighter along their edges. Secondaries 

 with a patch of dusky near the end, which on the innermost three or four becomes 

 restricted to the outer web. First primary, with about half the inner web along the 

 shaft, black ; second and third with the outer webs wholly black, and a narrow line of 

 black on the inner, along the shaft. Tail with a subtcrniinal brownish-black bar. 



Very young. — Bill flesh-color, dusky on the terminal half. Crown of head, and neck 

 behind to the interscapulars, clouded with dusky bluish-gray, heightening on the sides 

 of the neck into light grayish-ochrous. Scapulars and middle of the back light gull- 

 blue, as in the adult, *but the feathers so broadly (for i inch) tipped with grayish-brown, 

 fading into dull white at tip, that the original color is nearly lost. Lesser wing-coverts 

 and tertials Inownish-black, the latter edged with the color of the edgings of the back. 

 Bastard quills and feathers along the edge of the wing variegated with black and white. 

 Primaries b!ack ; the outer two-thirds of the inner vane ot the first four bluish-white 

 to near the cud ; both vanes of the others of that color for a little distance ; the extreme 

 tips of all but the two first, white. Secondaries light gull-blue, each with a large ter- 

 minal blackiish spot continuous with the black ends of the inner primaries. Tail with 

 a broad terminal bar of black, and very narrowly tipped with dull white. 



IJimensionij. — Length, 14 inches ; extent, 32 ; wing, 10.25 ; bill above, 1.20 ; gajje, 1.75 ; 

 height at nostrils, 0.25 ; tarsus, or middle toe and claw, 1.40. 



Anaiomici I cliaraeterb. — The median palatal ridge is well defined, broad, beginning 

 six-tenths if an inch from the tip. Just at its centre the aperture of the posterior 

 uares begins. Anteriorly it is thickly i)apillate along its median line ; posteriorly there 

 are papillaj only on its edges and terminally. The two lateral palatal ridges, separated 

 from the median by a rather illy-defined sulcus, do not, as usual, terminate abruptly 

 in a papilhited raised extremity, but gradually lose themsehes in a fold of mucous 

 membrane at the angle of the mouth. The posterior vaulted space is well defined; 

 bounded posteriorly by a quadrant of well-developed slender acute papillte. Tongue 

 measures a little more than an inch, of the ordinary shape and consistency. Nasal 

 aperture O.s-jO long. 



