SWANS AND ALLIED SPECIES. 647 



long, rather broad, convex, the second and third quills 

 longest, the first little shorter ; the tail short, rounded, of 

 from eighteen to twenty-four feathers. 



Gregarious, migratory, flying in] lines when journeying. 

 They feed on vegetable substances, swim with ease and very 

 gracefully, keeping the neck curved and the wings somewhat 

 raised. They have a strong and rapid flight, never dive 

 when searching for food, and walk slowly and rather un- 

 gracefully. They differ little from the Anserinae and Anatinse> 

 from which, however, they are easily distinguishable by their 

 great size, together with their comparatively short legs and 

 very elongated neck, as well as their large and peculiarly 

 shaped bill, of which the breadth is nearly uniform. A 

 curve or loop of the trachea, which is contained in a cavity 

 in the substance of the sternum, exists in most of the 

 species. 



SYNOPSIS OF THE BRITISH GENERA AND SPECIES. 



GENUS I. CYGNUS. SWAN. 



Bill rather longer than the head, large, higher than 

 broad at the base, gradually becoming depressed, of nearly 

 equal breadth throughout, and rounded at the end; a bare 

 space between the eye and the base of the bill ; tarsus short, 

 stout, considerably compressed, reticulated with small angular 

 scales ; hind toe free, very small, elevated, compressed be- 

 neath ; anterior toes longer than the tarsus, reticulate as far 

 as the second joint ; interdigital membranes full ; claws 

 strong, arched, compressed, rather obtuse ; feathers of the 

 head very small and oblong, of the neck narrow and soft, of 

 the other parts ovate and rounded ; wings very long, with 

 about thirty-two quills, the second and third longest ; tail 

 short, rounded, of from eighteen to twenty-four rounded 

 feathers. 



1. Cygnus immutabilis. Changeless Swan. About sixty 

 inches long; bill orange-red, with the unguis and a compressed 



