310 CANVASS-BACK DUCK. 



Length to end of tail, 2<H inches, to end of wings 18^, to end of claws, 

 23i; extent of wings, 30f; wing from flexure, 9i. Weight 2 J lbs. 



This species is very closely allied to the Pochard, or Red-headed Duck, 

 FuUgula 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 neck; and the white 

 spot on the chin is wanting in the Pochard. 



The Digestive and Respiratory Organs of a male shot near Baltimore pre- 

 sent the following characters. 



The upper mandible is broadly and deeply concave. The tongue, which 

 is thick and fleshy, as in other Ducks, is 2 T 2 2 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 

 T 5 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 yf, the tendons large and strong. The transverse diameter of the 

 gizzard is 2\^ inches, the longitudinal, from the cardiac orifice to the bulge 

 of the inferior muscle, 2-^\. 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 of the liver, proceeds backward be- 

 neath 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 T % to T %, enlarged again to T 6 2, 

 and so continuing to the rectum, which is 6 inches long, ^ inch in diameter, 

 and ends in an enlargement or cloaca, about an inch in diameter. The cceca, 

 which commence at the distance of 6 inches from the anus, are 8 inches long, 

 slender, -^ in diameter for 3 inches, afterwards about T 3 2, with the extremity 

 obtuse. The oesophagus and stomach contained young shoots of Zostera 

 'marina, and in the latter were numerous particles of quartz. 



