American Wild Swan. 87 
external specific differences between his two English swans, I have 
taken particular care to ascertain, beyond a doubt, the tint in the 
American bird, and find it ranges from a pure gamboge yellow to a 
bright red-orange, and without any regard to sex or age, except in the 
yearling, as above mentioned, when it is covered by small feathers. 
This mark is always in the same position. ‘The feathers continue, 
except at the anterior fourth where the yellow spot reaches them, to 
the very edges of the eyelids, which are yellow. In every case, the 
bill has been one eighth of an inch narrower at the middle than near 
the point, and in all young birds, where the plumage had become 
white, a dirty yellow tinge around the head and back of the neck, 
marked its immaturity. 
In several instances, a well defined yellow or orange line ran from 
the point of the feathers, between the legs of the lower bill, forward, 
to their junction at the point, and sometimes ended in a large patch of 
the same color. In every case, the tail had twenty feathers, although 
in the younger ones, there were several of them still in the sheath. 
The other external characters are common to the genus. 
The internal arrangements are those, in a great degree, of the Be- 
wick swan. The wind-pipe is unifcerm in calibre, and entering the 
keel, takes the circuit of the horizontal pouch in the posterior flatten- 
ed portion of the bone, and returning out of the keel at the same ori- 
fice it entered, winds round the merry-thought and goes to the lungs. 
Plate II, fig. 1. 
In the specimen whose admeasurement is given in detail, the loop 
of the trachea occupied a posterior cavity of two inches in transverse 
diameter, leaving in the hollow of the loop, one inch of vacant space, 
and projecting one third of an inch above the inner surface of the ster- 
num, but showing norise externally. In another preparation I possess, 
(Plate I, fig. 1.) from a bird of equal age, the sternum is seven inch- 
es and a half in a straight line drawn across the concavity of the in- 
ner surface, and the posterior chamber extends to the extreme back 
edge of the bone, the trachea penetrating the whole distance. In 
this case, the horizontal chamber is three inches and one fourth in 
transverse diameter, and spreads, on one side, three fourths of an’ 
inch beyond the edge of the breast-bone, and covering and resting on 
the ribs to that distance. ‘The vacuity in the loop is two inches in 
diameter. A third instance gives a bone seven inches and a half 
long, with the trachea extending to the very posterior edge, and the 
chamber in the bone two inches and three fourths across, and cover- 
ing the whole breadth of the sternum. 
