AMERICAN SWAN. 683 



•wider toward the end, which is rounded. The upper man- 

 dible has the dorsal line sloping, the ridge at first flat and 

 broad, but gradually narrowed to beyond the nostrils, then 

 convex, the sides nearly erect at the base, gradually sloped 

 and more convex, the unguis broadly obovate, large, and con- 

 vex, with the edge strong and internally striated, the edges 

 soft, marginate, and scrobiculate. The lower mandible with 

 the intercrural space very long and of moderate width, its 

 membrane bare for two-thirds, the crura convex beneath, 

 their lower outline slightly rearcuate, the laminated margins 

 inclinate, the unguis very large, obovato-elliptical, with a 

 broad groove at each side ; the gape-line slightly rearcuate. 



The upper mandible is deeply concave, with a medial 

 papillate ridge, and on each side an oblique series of trans- 

 verse flattened tubercles, a sub-marginal series of inconspicu- 

 ous, slender lamellge, and thirty-five oblique and transverse 

 slender, elevated, obtusely terminated laminse, of which the 

 slightly elevated free tips do not project beyond the margin. 

 On each side of the lower mandible are about twenty-two 

 external and sixty-five internal lamellae. The oesophagus, 

 thirty-three inches and a half in length, averages ten-twelfths 

 in width, but toward the lower part of the neck is enlarged to 

 one inch, and in the proven tricular part measures an inch 

 and a half in breadth. The stomach, which is placed very 

 obliquely on the left side, measures three inches in length, 

 four inches and eight-twelfths in breadth, being of a trans- 

 verse elliptical form, a little compressed, with the lateral 

 muscles extremely developed, the tendinous fibres covering 

 nearly the whole surface, the tendons very narrow in the 

 middle; the inferior muscle distinct and small. The intestine, 

 eleven feet ten inches in length, varies in width from an inch 

 and a quarter in the first part of the duodenum to eight- 

 twelfths of an inch. The duodenum curves round the edge of 

 the stomach in three- fourths of a circle, returns at the distance 

 of nine inches, receives the biliary ducts at nineteen inches 

 from the pylorus, then passes along the right side, near the end 

 of the abdomen, ascends, forms several curves beneath the 

 kidneys, and then forms several nearly transverse parallel 

 folds, extending from the duodenal fold to the anus, after 



