CANVASS-BACK DUCK. 13 
back, and with some of the scapulars faintly undulated with darker. 
Tail greyish-brown, paler at the end; axillars and smaller under 
wing-coverts white, as in the male. 
Length to end of tail, 20} inches, to end of wings 183, to end of claws, 
231; extent of wings, 302: wing from flexure, 93. Weigh 22 lb. 
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 proportionally 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 uni- 
form with the neck; and the white spot on the chin is wanting in the 
Pochard. 
The Digestive and Respiratory Organs of a male shot near Balti- 
more present the following characters. 
The upper mandible is broadly and deeply concave. The tongue, 
which is thick and fleshy, as in other ducks, is 2,4, inches long, its sides 
parallel, slightly sloping, and furnished with two series of bristly fila- 
ments; its base with numerous straight conical papilla directed back- 
wards, 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 cesophagus passes along the right side of the 
neck, for six inches has a diameter of ,5, then dilates to ;%, so as to 
form a slight crop, again contracts as it enters the thorax, and in ter- 
minating forms the proventriculus, which is 12 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 1} in thickness, 
the right }2, the tendons large and strong. The transverse diameter 
of the gizzard is 213 inches, the longitudinal, from the cardiac orifice 
to the bulge of the inferior muscle, 274. Its cuticular 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 
