26S 
ON THE DIFFERENT SPECIES OF 
5. Larus arcticus. Northern Gull. 
L. rostro inferne solum aucto, dorso alisque coerulescenti- 
perlaceis, pennarum versus apicem spatio magno albo, 
prioribus quinque albescentibus, alls caudam sequanti- 
bus (tarso digi toque 2a pollicum longis). 
Adult^ Summer Pkimage.'-rBeak moderate, deep, com- 
pressed, the upper outline without any prominence beyond 
the nostrils, upper mandible exceeding the under by about 
fths of an inch ; wine-yellow, diaphanous at the tip and 
edges, an orpiment-orange spot at the knob; length 2i 
inches, depth fths. Feet pale flesh-colour ; tarsus 2i inches, 
middle toe 2i. Wings reaching exactly to the end of the 
tail. Total length S5i inches, extent 50. Back and upper 
surface of wings pure pearl-grey, with a good deal of blue ; 
the outer primaries nearly all white, as well as their shafts, 
and the tips of all the quills. The rest of the plumage 
white. 
Note. — The above description is from a fine specimen 
brought by Captain Scoiiesby junior, from the coast of 
Greenland, in the autumn of 1822, and now in the Mu- 
seum. 
Adult, Winter Plumage, unknown, although from ana- 
logy it may be presumed to be distinguished from the sum- 
mer only by longitudinal streaks of pale brown upon the 
head and neck. 
Young. — There is a specimen in the Museum, which 
would seem to be the young of this bird ; it is from Ork- 
ney, and its description is as follows : 
Beak IJ in. long, fths deep, black at the end, dusky. 
