AMERICAN SWAN. 
234 
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 85 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 the 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 coeca, 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 8 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 coeca 11 inches long, their diameter for 
3 inches only 2 twelfths, in the rest of their extent from 3 to 41 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 6 inches 
c 
