Mr. Yarrell on a new Species of Wild Swan. 449 



the oldest and most perfect specimen of each sort I have been 

 able to procure during the present winter, exhibit the real dis- 

 tinctions in a manner not to be easily mistaken. 



New species. Hooper. 

 Weight ISflbs. 24 lbs. 



Ft. Inch. Ft. Inch. 



Point of the beak to the end of the tail 3 9 5 



Width with wings extended .... 6 1 7 10 



Point of beak to the edge of the forehead 3^ 4f 



eye 4f 5^ 



occiput .... 6^ 07 



Carpus to the end of the primaries . . 20^ 25 



Tail feathers in number 18 20 



Length of tarsus 3|- 4 



middle toe 5| 6i 



intestines 10 2 12 



cseca 10 11 



breast bone 6f ' 8^- 



Depth of insertion of the trachea within 5|- 3 



Length of bronchial tubes 1^ 3^ 



The anatomy of the Hooper is too well known to require 

 further notice, except on some points of comparison. The fold 

 of the trachea confined within the keel, never departs from the 

 vertical position in this species at any age ; nor have I ever 

 seen, in the oldest examples, the slightest appearance of exca- 

 vation in the sternum itself. In the new species, on the con- 

 trary, the trachea will always be found to have assumed the 

 horizontal direction in old birds ; and even when young, the 

 sternum is excavated to a greater depth ready to receive the 

 fold of the trachea, to be developed at a subsequent period. 

 The depth of the insertion of the fold of the trachea in the old 



3 M 2 Hooper 



