BUFFEL-HEADED DUCK. 221 
Individuals of both sexes differ much in size, and in the tints of 
their plumage. 
In an adult male, the tongue is 1 inch and 2 twelfths long, fleshy, 
and of the same general form as in the other ducks already described. 
The cesophagus is 62 inches long, passes along the right side, has a 
diameter at the top of 44 twelfths, enlarges about the middle to 9 
twelfths, and contracts to } inch as it enters the thorax. The proven- 
triculus is 1 inch long, 8 twelfths in its greatest diameter, its glandules, 
which are of moderate size, forming a complete belt, as in all other 
ducks. The stomach is a muscular gizzard of a roundish form, 1 inch 
5 twelfths long, 1 inch 4 twelfths in breadth; its lateral muscles 5 
twelfths in thickness ; its epithelium tough, hard, and slightly rugous. 
The intestine is 3 feet 11 inches long; its average diameter 3 twelfths, 
its walls thick, and its inner surface villous. The rectum is 3 inches 
long; the coeca 2} inches in length, their diameter at the commence- 
ment 1 twelfth, towards the end 2 twelfths. 
The trachea is 5 inches long, much flattened, its rings unossified, 
its diameter at the top 2% twelfths, towards the lower part 3 twelfths, 
having scarcely any appearance of dilatation at the part which is so 
excessively enlarged in the Golden-eyed Duck, which in form and ha- 
bits is yet very closely allied. The lateral muscles are strong, and 
there are cleido-tracheal and sterno-tracheal muscles, as in other ducks. 
