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 3i 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 f Faun. Bor. Amer.' These are de- 

 scribed as ff 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*. Remainder 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 1 \ inch in depth, 

 and diminishes in the succeeding: feathers. 



