234 



AMERICAN SWAN. 



Fig. 2. 



grinding surfaces considerably con- 

 cave, smoothish, of a horny texture, 

 1 inch 8 twelfths long, 1 inch 5 

 twelfths broad. There is a large 

 pyloric sac, from which the duode- 

 num, h i j k, comes off. It curves 

 round the edge of the stomach to the 

 length of 8^ inches, as represented 

 by Fig. 2, a b, forming three-fourths 

 of a circle, and reaching the sixth rib 

 on the left side; it then curves back 

 upon itself, b c, to above the stomach, 

 where it receives the biliary ducts, 

 passes upwards and backwards along 

 the spine until it nearly reaches the 

 anus, then returns forward as far as 

 the upper edge of the stomach, then 

 forms a small loop 3 inches long, 

 comes forward again, passes back- 

 ward, then forward, again backward 

 and forward, now becomes anterior, 

 and curves parallel to tbe duodenum, reaching the seventh rib, then passes 

 backward, parallel to itself, as far as the liver, curves again in the same 

 direction, and proceeds backward, then sweeps backward behind to near the 

 anus, where it becomes accompanied by the cceca, comes forward on the 

 right side to the anterior edge of the stomach, bends abruptly backwards, and 

 terminates in the anus. It thus forms 16 curves or S folds. Its length is 11 

 feet 5 inches, its average diameter 7 twelfths. The rectum is 7 inches in 

 length, 8 twelfths in diameter. The cceca 11 inches long, their diameter for 

 3 inches only 2 twelfths, in the rest of their extent from 3 to 4^- twelfths, 

 the extremity obtuse. The cloaca is of moderate size and of a globular form, 

 with longitudinal rugae on its inner surface; that of the rectum is also 

 longitudinally rugous, and covered with flattened papillae. The transverse 

 muscular fibres of the intestine are all very well marked in its whole extent; 

 the inner surface is covered with minute prominences, arranged in regular 

 series; the anterior portion beautifully villous. 



This species has 11 ribs, the anterior rib not joining the sternum. The 

 lungs are of large size, extending from the second to the ninth rib, and 

 having, therefore, 7 deep grooves on their upper and inner surface. The 

 trachea is 20 inches long; its breadth at the anterior part 9 twelfths. It 

 gradually diminishes to 7 twelfths, and is much flattened until about G inches 



