146 AMERICAN SWAN. 



" In several instances, a well-defined yellow or orange line ran from 

 the point of the feathers, between the legs of the lower mandible, forward, 

 to their junction at the point, and sometimes ended in a large patch of 

 the same colour. In eioery case, the tail had twenty feathers, although 

 in the younger ones, there were several of them still in the sheath. 

 The other external characters are common to the genus. 



" The internal arrangements are those, in a great degree, of the 

 Bewick Swan. The windpipe is uniform in calibre, and, entering the 

 keel, takes the circuit of the horizontal pouch in the posterior flattened 

 portion of the bone, and returning out of the keel at the same orifice 

 it entered, winds round the merry-thought and goes to the lungs. 



*' In the specimen whose admeasurement is given in detail, the loop 

 of the trachea occupied a posterior cavit}^ of two inches in transverse 

 diameter, leaving in the hollow of the loop, one inch of vacant space, 

 and projecting one-third of an inch above the inner surface of the ster- 

 num, but shewing no rise externally. In another preparation I pos- 

 sess, from a bird of equal age, the sternum is seven inches and a half 

 in a straight line drawn across the concavity of the inner surface, and 

 the posterior chamber extends to the extreme back edge of the bone, 

 the trachea penetrating the whole distance. In this case, the horizon- 

 tal chamber is three inches and one-fourth in transverse diameter, and 

 spreads, on one side, three-fourths of an inch beyondthe edge of the breast- 

 bone, and covering and resting on the ribs at that distance. The va- 

 cuity in the loop is two inches in diameter. A third instance gives 

 a bone seven inches and a half long, with the trachea extending to the 

 very posterior edge, and the chamber in the bone two inches and three- 

 fourths across, and covering the whole breadth of the sternum. 



" Another preparation, six inches and one-half long, of a younger 

 Swan than either of the preceding, developed a rising on the internal 

 surface of one inch in diameter, with the trachea entering but four in- 

 ches and three-fourths, and just assuming the horizontal position ; and 

 the very young bird, already mentioned, and which was no doubt a 

 yearling cygnet, produced a sternum six inches and one-half in length, 

 with the trachea entering three inches and one-half, and preserving a 

 vertical fold, and shewing merely a gentle swelling in the bone at the 

 posterior termination of a cavity four inches deep. In every instance, 

 the trachea, upon approaching this horizontal apartment, takes to the 

 right to sweep round the cavity. The two portions uf the tube, although 



