

BEWICK'S SWAN. 203 



of the bone of divarication, and to a slender semicircular 

 bone on each side, by which it is supported. 



The muscles of voice with which this bird is provided 

 pass down, as usual, one on each side of the trachea, till 

 the tube is about to enter the cavity in the keel, they then 

 quit that part of the tube to be attached to the ascending 

 portion of the curve, which they follow, ultimately di- 

 viding into two slips, one of which inserted upon the sur- 

 face of the bone of divarication governs the length of the 

 preceding flexible portion of the tube ; the other slip 

 passes off downwards to be attached to the inner surface 

 of the breast-bone, anterior to the first rib. The course 

 of the muscle on one side may be traced in the first ana- 

 tomical figure. 



The vignette at the end of this subject represents a front 

 view of a portion of the body of this species of Swan, with 

 the anterior part of the descending windpipe turned aside 

 to show the inner ascending part of it, the muscles of 

 voice, and the tendinous fascia stretched across from one 

 branch of the forked bone or merrythought over to the 

 other, by which both portions are supported. 



Dissection, which proved the distinction between the 

 Hooper and Bewick's Swan, has also proved that the two 

 Wild Swans of North America are peculiar to that country, 

 and distinct from the two European Swans. The largest 

 of the North American Swans, still larger than our Hoo- 

 per, is called Cygnus buccinator, or the Hunter's Swan, 

 by Dr. Richardson, in his Fauna Boreali- Americana, where 

 the measurements and other particulars of its history will 

 be found ; and I am indebted to the liberality of Dr. 

 Richardson for a specimen of the very singular organs of 

 voice and the sternum of this species, which will be found 

 described and figured in the seventeenth volume of the 

 Transactions of the Linnean Society. 



