194 Mr. W. Thompson on the Occurrence of the 
mandible where the plumage ends, it is 2^ lines in breadth, 
whereas the depth at the same place is S~ lines. In colour it is 
black ; paler at the base beneath. Tarsi, toes and webs of feet 
of a uniform pale flesh colour as the legs ” of the young male 
are described to be in the ^ Faun. Bor. Amer.^ These are de- 
scribed as carmine-red” in the adult. In the specimen under 
examination they are just the colour that I have remarked those 
of the nestling Larus ridibundus to be, and which it retains 
through the following autumn and winter ; the adult of this spe- 
cies having these parts of an arterial blood-red. The claws are 
blackish and dark brown. Inside of the mouth pale reddish 
flesh-colour : — described to be carmine in the adult. The tail 
may be termed even at the end, very slightly rounded laterally.” 
The beautiful long tern-like wings were to me the most striking 
character at the first glance, and indicated what it was after- 
wards found had been remarked by Audubon, viz. that — “ the 
flight of this gull is light, elevated and rapid, resembling in 
buoyancy that of some of our Terns more than that of most of 
our Gulls, which move their wings more sedately.” 
Plumage. Head white, excepting the usual blackish seasonal 
ear-spot of Xema ; a little of this colour before the lower portion 
of, and beneath the eye, and a little above it posteriorly — also 
blackish mixed with white on the nape. Thence to the back very 
pale pearl gray ; back or mantle manteau,” Temm.) pearl or 
pale bluish gray. Tail pure white except from about a line in- 
wards from the tip, where a band of black nearly an inch in 
breadth appears. The wings exhibit generally the bluish gray 
of maturity, but have clove brown markings on the bastard 
wing, lesser coverts and scapulars ; anterior border of the wing 
white from its shoulder for the breadth of four greater primary 
coverts.” Primaries exhibiting in degree considerably more black 
than the specimen described in ^ Faun. Bor. Amer.^ — outer mar- 
gin of the first entirely black ; of the second, from tip upwards 
for 5^ inches black, thence white ; of the third, from the tip up- 
wards black for 4 inches next the shaft, for 3^ inches on outer 
margin*. Bemainder of the primaries terminated with brownish 
black except at the extreme tip. On the third, the first indication 
of white appears in a mere line of that colour, thence it becomes 
gradually larger in size and deeper in shade to the seventh, where 
it assumes the pearl gray of the lower portion of the same feather. 
The black becomes more and more tinged with brown from the 
* Dr. Richardson remarks that, — “ the extent of black on the ends in- 
creases gradually from the first to the fourth, on which it measures above an 
inch, diminishing again in the following ones.” In my specimen the extent 
of black increases gradually only to the third, in which it is inch in depth, 
and diminishes in the succeeding feathers. 
