cafvass-bace: duok. 
21 
Length to end of tail, 20i inches, to end of wings 184, to end of claws, 
23£ ; extent of wings, 3 Of ; wing from flexure, 9£. Weight 2| lbs. 
This species is very closely allied to the Pochard, or Red-headed Duck, 
Fuligula Ferina, but is much larger, and differs in having the bill propor- 
tionally higher at the base, and less dilated towards the end. The colours 
are also generally similar, but present differences. The upper parts of the 
Canvass-back are much whiter than those of the Pochard ; the head of the 
former is dusky above, of the latter uniform with the necl?; and the white 
spot on the chin is wanting in the Pochard. 
The Digestive and Respiratory Organs of a male shot near Baltimore 
present the following characters. 
The upper mandible is broadly and deeply concave. The tongue, which 
is thick and fleshy, as in other Ducks, is 2fV inches long, its sides parallel, 
slightly sloping, and furnished with two series of bristly filaments ; its base 
with numerous straight conical papillae directed backwards, its upper surface 
marked with a broad median groove, the lower flat, its extremity formed by 
a thin semi-circular appendage, a quarter of an inch in length. The oesopha- 
gus passes along the right side of the neck, for six inches has a diameter of 
r S 2 , then dilates to T 9 2 , so as to form a slight crop, again contracts as it enters 
the thorax, and in terminating forms the proventriculus, which is If inches 
in length, with oblong glandules, generally a twelfth of an inch in length. 
The stomach is a very large and powerful gizzard, of a broadly elliptical 
form, with extremely thick lateral muscles, the left being \\ in thickness, 
the right the tendons large and strong. The transverse diameter of the 
gizzard is 2f| inches, the longitudinal, from the cardiac orifice to the bulge 
of the inferior muscle, 2 T V* Its cutioular lining is of very dense texture, 
and rugous ; the grinding plates opposite the lateral muscles about half a 
twelfth thick, and slightly rugous. The intestine, which is 5 feet 9 inches 
in length, first forms in the usual manner the duodenal fold, at the distance 
of 5 inches from the pylorus, encloses the pancreas, receives the biliary 
ducts, and passing under the right lobe of the liver, proceeds backward 
beneath the kidneys, is convoluted in several large folds, and finally from 
above the stomach, passes in a direct course to the anus. Its coats are 
thick, its inner surface villous, and its diameter is considerable, being in 
the first part of the duodenum T 9 2 , then for two feet from fV to j enlarged 
again to T2! and so continuing to the rectum, which is 6 inches long, i inch in 
diameter, and ends in an enlargement or cloaca, about an inch in diameter. 
The coeca, which commence at the distance of 6 inches from the anus, are 8 
inches long, slender, T \ in diameter for 3 inches, afterwards about T \, with 
the extremity obtuse. The oesophagus and stomach contained young shoots 
of Zostera marina, and in the latter were numerous particles of quartz. 
