CHANGELESS SWAN. 655 



upper mandible with its outline declinate and concave, at the 

 end decurved, the sides slightly sloped at the base, gradually 

 more inclined and convex toward the end, the edges soft and 

 marginate, with the lamellae projecting a little, the unguis 

 oblong, broad at the end, convex, deciirved, strong-edged ; 

 the lower mandible very slightly rearcuate, its unguis trian- 

 gular. 



On the concave roof of the mouth is a medial series of 

 large flattened tubercles, and on each side at the base an 

 oblique row of similar tubercles, then a lateral series of very 

 slender, inconspicuous elevated lines and grooves, and fifty- 

 two marginal lamellae, of which the outer extremities are 

 compressed and obtuse. On the lower mandible are about 

 fifty external lamellae, of which about twenty-two only are 

 very distinct, and ninety marginal lamellae. The tongue is 

 three inches and a quarter in length, ten-twelfths in breadth, 

 fleshy, with the sides parallel, the base with a double semi- 

 circular series of conical papillae, a large soft prominence 

 above, a deep medial groove having on each side flat, acute, 

 spreading papillae, the edges fringed with papillae, of which 

 the posterior are large, the anterior small, and an inferior 

 series of filaments, extending behind the base of the tongue. 

 The oesophagus, thirty-eight inches long, varies in width from 

 eight-twelfths to an inch and a quarter, being dilated at the 

 lower part of the neck. The proventriculus is an inch and 

 eight-twelfths in breadth. The stomach is obliquely situated, 

 three inches and a half in length, four inches and a quarter 

 in breadth, a little compressed, less oblong than in the other 

 species, with extremely developed lateral muscles, very large 

 tendons, and rugous epithelium, with two concave grinding 

 surfaces. The intestine is sixteen feet and a half in length ; 

 its duodenal part an inch in width, the rest six-twelfths. 

 The duodenum curves at the distance of eight inches, and 

 receives the gall-ducts at that of twenty. The rectum is nine 

 inches and a half in length, at first nine-twelfths in width, at 

 the end dilated to an inch and a half. The coeca are fifteen 

 inches long, for five inches only two-twelfths and a half wide, 

 then enlarged to ten-twelfths, and toward the end decreasing 

 to five-twelfths. 



