210 MERGANSER CASTOR. 



part of the tympanum ; the distance from their bases being 

 nearly an inch. The expanded part is two inches in length, 

 an inch and five-twelfths in breadth, its greatest diameter 

 two inches and two-twelfths. Having described this curious 

 apparatus, I must apply to the system-makers, who are in- 

 dignant at being supposed ignorant of anything, for its uses. 

 The nostrils are oblongo-elliptical, four-twelfths long, 

 sub-medial, lateral, pervious. The eyes small, as are the 

 apertures of the ears. The feet are very short, strong, and 

 placed far behind. The tibia is bare for about a quarter of 

 an inch. The tarsus very short, much compressed, with an 

 anterior series of twenty-five, and twelve outer scutella, the 

 sides with small, angular scales. The first toe very small, 

 elevated, arched, with about ten scutella, and a lobiform 

 membrane ; the second with a two-lobed inner membrane, 

 and about thirty-five oblique scutella ; the third with forty- 

 two, the fourth, a little shorter than the third, and with forty 

 scutella. The interdigital membranes emarginate. The 

 claws are small, a little arched, compressed, obtuse, that of 

 the hind toe very slender and more curved, that of the third 

 somewhat depressed and rounded. 



The plumage is moderately full, dense, soft, and glossy. 

 The feathers on the head and neck silky, blended, along 

 nearly the whole breadth of the head and on the nape elon- 

 gated so as to form a broad short crest, not very conspicuous. 

 On the back the feathers are rather compact, on the lower 

 parts blended. The wings are short, of moderate breadth, 

 with thirty-six quills ; the primaries narrow, tapering, stiffish, 

 the first longest, the rest rapidly decreasing, the outer second- 

 aries rather short, rounded, the inner elongated and tapering, 

 but obtuse ; the scapulars also very long. The tail is short, 

 much rounded, of eighteen rather narrow, stiffish, obtuse 

 feathers, of Avhich the medial are an inch and three-fourths 

 longer than the lateral. 



The bill is bright vermilion, with the unguis black, and 

 the ridge of the upper mandible, and part of the crura of the 

 lower, dusky. The iris bright red. The feet bright vermi- 

 lion, the claws reddish at the base, grey toAvard the end. The 

 head and upper half of the neck are black, with bright green 



