642 LAEUS HEERMANNI, WHITE-HEADED GULL. 



on the neck into plumbeous ash, which extends oTcr the whole under parts, being 

 lighter on the abdomen and under tail-coverts than elsewhere. The baois is deep 

 plumbeous slate, lighter on the rump. Upper tail-coverts clear ashy. Upper surfaces 

 of wings like the back ; the primaries black ; the tips of all, except the two or three 

 outer ones, narrowly white. Tail black, narrowly tipped with white. Legs and feet 

 reddish-black. 



Yomg-ef-the-year.—Smallev than the adult. Bill and feet brown ish-blaek. Entire 

 pliunage deep sooty or fuliginous blackish ; all the feathers, but especially those of 

 the back and upper wing-coverts, edged with grayish-white. Primaries and seconda- 

 ries black, as in the adults, with only traces of white tips on the former. Tail black, 

 very narrowly tipped with dull white. 



Immature. — Considerably larger than the above-described adult, the length being 

 from 18 to 21 inches. Bill as in the adult. Head all round, and the throat, mottled 

 with brownish-black and dull white, the latter color predominating on the forehead 

 and throat. Upper tail-coverts lighter than in the adult, and the white tips of the tail- 

 feathers broader^ otherwise generally as in the adult, but with all the colors rather 

 deeper. 



Dimensions.— "i^ength, about 17.50; wing, 13.50; tail, 5.50." (No. 58797, Isabella 

 Island, adult) : Length of skin, 18.50 ; wing, 14 ; tail, 5.75 ; bill along culmen, 1.80 ; 

 along gape, 2.40 ; depth at base, 0.55 ; at angle, about the same ; tarsus, 2.20 ; middle 

 toe and claw, a little less. (No. 30t;4^l, Guatemala, young) : Wing, 12.25 ; tail, 4.75 ; bill 

 along culmen, 1.60 ; depth at base, 0.50 ; at angle, 0.45 ; tarsus, 1.90. Length of some 

 skins up to about 20 inches. 



This species varies materially in size, though not beyond the usual limits in this 

 family. The £gure8 above given are near the extremes I have observed. At first the 

 bird is a nearly uniform smoky-brown all over, with blackish quills and tail-feathers, 

 usually varied with whitish edgings of .the feathers of the upper parts, particularly 

 those of the scapulars and wing-coverts. The bill is pale, with a dark tip. This stage 

 gives way to a slaty plumage, paler below, with the ends of the secondaries and the 

 upper tail-coverts growing more and more pale ashy, the tail acquiring a whitish tip, 

 the head mottled with fuscous or whitish, and the bill reddening. With the clearing 

 of all these colors, the head grows pure white, gradually shading into the slaty-ash of 

 the fore-parts. The feet appear to be always blackish. The first and final stages are 

 excellently wellxepreseutedin ilr. Cassin's plate, above cited. 



This species seems to me to be thoroughly established. Soon after its original de- 

 scription.Mr.Lawrence noted some similarity of its characters to the description of Larue 

 helcjieri, Vigors, and likewise of ir/rHs/iiZiginosHS, Gould, suggestiug a prohable identity. 

 Prof. Schlugel went further, unhesitatingly uniting the three, an error that I unfortu- 

 nately adqpted in the "Key;" being at that time without the means of satisfying 

 myself. .Latterly Messrs, Sclater and Salvin have unraveled the synonymy of these 

 and some allied species, showing that they are perfectly distinct. I have lately gone 

 over the Smithsonian serieis, in company with Mr. Salvin, finding the specimens, as far 

 as they go, to verify all the points given in the paper just referred to. L. fuliginosus, said 

 to be only. from the Galapagos, I have not seen ; the specimens before me are of vw- 

 destiis, lieermaiini, and Mcheri. The latter are labeled by Mr. Cassin " L. fuliginosus 

 Gould,";and are those referred to in his Ornithology of the United States Exploring 

 Expedition, ,1858, p. 378, under such name. An older label on each of the same speci- 

 mens says " h(smatorhynchus Uing," apparently Mr. Peale's original identification; 

 whereas. Mr. Salvin points out to me that the birds are neither fuliginosus nor licemator- 

 hynchus ^=seo-resT)yi Traill), but are helcheri Vigors. This wrong labeling, which I had 

 no reason to suspect, was what threw me off- the scent altogether. Granting these 

 specimens to be JbeJcheri, they are altogether different from heermanni, as claimed by 

 Messrs. Sclater and Salvin. They are much larger ; the bill and feet, in particular, are 

 very mueh larger /and stouter..; the mantle, instead of being slaty-gray, is of a blackish- 

 slate, much as in L, dominicanus. Most of the under parts, and the upper tail-coverts 

 and endS'Of the secondaries, are.ashy white. The tail, instead of being black, white- 

 tipped, may be better described.as white, with a broad, black subterminal bar — indeed 

 the outer web of the outer ieather is entirely white ; the black bar on the inter web 

 of this feather is only about an inch broad, and on the middle feathers is only about 

 half as bread as the tail is long. The bird is not a " white-headed " Gull at all, having 

 a dark hoetl like the mantle. ■J-also verify the curious restriction of the frontal antia;, 

 as flguredby the authors just mentioned. Wing, 14.25 ; tail, 5.50 ; bill along culmen, 

 2 ; its depth, at angle, 0.70 ; the aEgle well defined, the tip obtuse, the whole bill very 

 stout ; depth at base, about the same as at angle ; tarsus, 2.40. The bill in its present 

 state is light^eolored, with a. dark subterminal zone, and the tarsi are rather light, but 

 the bird Jias'heen dried many years .(described from No. 15693 Callao, Peru). No. 15692, 

 from the same locality, is altogether similar. No. 15513, from Orange Bay, Terra del 

 Fuego, is a. very young bird, in the smoky-brown state of plumage, like that of heer- 

 mainii, but very extensively varied with whitish on the upper parts; and although so 

 young, the tail is already whitening at the base. These three specimens are the basis 

 of " liwmaim^j/nclnis Peale, 184S, Mec King," and of "fuliginosMs Cassin, 1858, nee Gould." 



