NATURAL SCIENCES OF PHILADELPHIA. 
303 
•it, somewhat so before it. Commissure about straight to near the tip. Tarsus 
about equal to middle toe and claw. Adult : Bill bluish green, its terminal 
third bright yellow. Legs and feet dusky bluish green, the webs yellowish. 
Mantle light grayish blue, or dark pear) blue ; a shade lighter than in canus , 
much darker than in Delawarensis. Primaries : The bluish gray bases rather 
lighter than in canus, much darker than in Delawarensis, but fading into nearly 
pure white on all but the first, at its juncture with the black portion. These 
bluish gray bases extend towards the end much further than in canus , as far 
as in Delawarensis ; and, as in that species, extend on the second, third and 
fourth feather further along the centre of the feather than on the edges, so 
that they are bordered for some distance with the black of the terminal por 
tions. The black takes in the outer web of the first primary, and nearly the 
whole of the inner, but rapidly becomes narrower, till on the sixth it is merely 
a subterminal transverse bar ; the seventh has frequently a spot of black on 
one or both webs ; first, with a large white spot near the end, two inches long, 
longer on the outer than on the inner web, not divided by the black shaft ; 
the tip of the feather black ; second, with a similar spot, but smaller, not 
longer on the outer than on the inner web, and divided by the black shaft ; 
the extreme tip white, as are the apices of all the others except the first. 
Dimensions: Length 17’50 ; extent 40*00; wing 13-75. Bill above 1-40; 
along gape 2-00; height at nostril and at angle *35 ; tarsus and middle toe 
and claw 1-80. 
Habitat . — Interior of Arctic America. North Pacific Coast. 
I have before me the type specimen of Richardson’s Larus brachyrhynchus, the 
original of this description in the Fauna Boreali-Americana, “ a female, killed 
on the 23d of May, 1826, at Great Bear Lake.” “ Some brown markings on 
the tertiaries, primary coverts, and bastard wing, with an imperfect subter- 
minal bar on the tail, point it out as a young bird, most probably just com- 
mencing its second spring. The rest of its plumage corresponds with that of 
Li zonorhynchus, except that it wants the extreme white tips of the quill 
feathers.” The specimen is labelled “ $, May 23, 1826, Great Bear Lake,” 
and corresponds minutely with the above description. Richardson, however, 
in drawing up the description from the young bird, fell into the error of 
giving ^ remi gibus apice concoloribus,” whereas, in the adults, the primaries 
are as broadly tipped with white as in Delawarensis or canus. In the type the 
bill is very short, perhaps less than in the average of even young birds ; but 
there are specimens before me in which it is quite as short. 
A very careful comparison of the types of Larus Suchleyi and Rissa septen- 
trionalis with the above specimen, and with the very extensive series of all- 
ages in the collection, shows them to be absolutely identical, and proves that 
the three names refer to one and the same species. 
The rather intricate discussion of the relationships of Larus niveus, Pallas, is 
presented elsewhere. The amount of the other synonyms may be stated in 
a word. There are in North America two species of “ Mew-Gulls.” One is 
the Delawarensis, Ord., zonorhynchus , Richd. The other is a bird, the adult of 
which Richardson mistook for the European canus, Linn, and so named it. 
the young of which he characterized as L. brachyrhynchus. The error of 
authors is in not recognizing two species, but considering canus, Rich., and 
brachyrhynchus, Rich., as intermediate ages, or varieties of zonorhynchus, Rich. 
As the name of canus is pre-oceupied, brachyrhynchus, though based upon the 
young bird, must stand for the North American species. 
Comparison of L. canus, Linn., of Europe, and L. brachyrhynchus, Rich., of 
America. — Common characters : Small weak bills, without strongly developed 
angle, or black band ; color of back nearly the same, subterminal and apical 
spots of primaries identical. Distinctive characters : brachyrhynchus has 
the bill shorter and smaller, culmen more convex at the end, the 
angle perhaps comparatively more developed. Size is less, gull blue, a little 
1862.] 
