446 Mr. Yarrell on a new Species of Wild Swan. 



numerous. More than fifty were counted in one flock at Wit- 

 tlesey-mere. Among a considerable number which have been 

 forwarded to the London markets for sale, I have been most 

 unexpectedly fortunate in securing five examples of this new 

 species, of different ages ; and possessing thus a series of gra- 

 dations in structure, which it is the object of this memoir to 

 describe, I have no doubt of proving them to belong to a spe- 

 cies entirely distinct, though hitherto confounded with our more 

 common winter visitor the Hooper ; ornithologists having as yet 

 admitted but one species of Wild Swan in their systematic cata- 

 logues of European Birds. 



In size the new species is one-third smaller than the Hooper 

 at the same age. The plumage is first grey, afterwards white, 

 tinged with rust-colour over the head and on the under surface 

 of the belly, and ultimately pure white. The beak is black at 

 the point, and orange-yellow at the base ; this last colour ap- 

 pears first on the sides of the upper mandible, and afterwards 

 covers the upper surface in front of the forehead, to the extent 

 of three quarters of an inch, receding from thence by a convex 

 line to the lower edge of the mandible at the gape ; the nostrils 

 are oblong and open ; the irides orange-yellow ; the wings 

 have the second and third primaries the longest and equal, the 

 first and fourth half an inch shorter than the second and third, 

 and also equal ; the tail consists of eighteen feathers, gra- 

 duated, cuneiform; the legs, toes, and claws, black. 



In anatomical structure the new species diflfers much more 

 decidedly from the Hooper than in its external characters. The 

 principal difference is in the trachea, which forms one of the best 

 distinctions in the separation of nearly allied species throughout 

 this numerous family. 



The tube of the wind-pipe is of equal diameter throughout, 

 and descending in front of the neck enters the keel of the ster- 

 num, M'hich is hollow as in the Hooper, traversing its whole 



length. 



