156 
ANSERINE. CYGNUS. 
239. Cygnus immutabilis. Changeless Swan. 
Adult male about sixty inches in length, ninety-eight in 
extent of wings ; bill from the joint to the tip of the upper 
mandible four inches and two-twelfths, from the knob three 
inches and a half, from the eye five inches and four-twelfths, 
its greatest breadth an inch and four and a half twelfths ; 
the forehead elevated, with a compressed fleshy lobe occupy- 
ing the basal angle of the bill ; tarsus four inches and a 
quarter ; middle toe five inches and eight-twelfths, its claw 
an inch ; tail of twenty-four feathers, rounded ; bare space 
on the forehead and between the eyes and bill black ; bill 
orange-red, except the unguis, which is black, and of a nar- 
row oblong form ; feet dull grey ; plumage pure white. Fe- 
male similar to the male, but considerably smaller. Young 
said to be white in their first plumage, in which respect they 
differ from those of the tame Swan. The trachea does not en- 
ter the sternum. (Esophagus thirty-eight inches long ; gizzard 
transversely and broadly elliptical, four inches and a quarter 
in breadth ; intestine sixteen feet and a half in length ; cceca 
fifteen inches long, rectum nine. 
Male, 64, 96, 25, 4 T %, 4J, 5 T V, fj-. Female, 58, 88. 
This species was discovered, described, and named by Mr 
Yarrell, from specimens shot on the east coast of England. 
It differs little from the tame Swan, but has the knob at the 
base of the upper mandible smaller, and the feet dull grey, 
instead of being black. I have examined and minutely de- 
scribed two individuals, which were kept in the Edinburgh 
Zoological Gardens. One of the humeri of the male had been 
fractured and reunited ; but how they were obtained I am 
unable to discover. 
Cygnus immutabilis, Changeless Swan, Yarrell ; also Mac- 
Gillivray, Brit. Birds, v. 
240. Cygnus musicus. Whooping Swan. 
Adult male about sixty inches in length, ninety-five in ex- 
tent of wings ; bill from the joint to the tip of the upper 
mandible three inches and a half, its greatest width about 
the middle an inch and a quarter ; from the eye to the tip of 
the bill five inches and two-twelfths ; tarsus four inches and 
two-twelfths ; middle toe four inches and ten-twelfths, its claw 
an inch ; tail of twenty feathers, rounded ; bare space on the 
forehead and between the eyes and bill, bright yellow, as is 
the base of both mandibles, that colour extending in an angu- 
