CYGNUS. 475 



The birds in the genus Tadorna may be further distinguished from 

 those in Anas by their larger size, white shoulders, and the prevalence of 

 chestnut in their colours. Fuligula and Somateria can only be regarded as 

 distinct on sufferance, to prevent too great change of nomenclature : they 

 completely intergrade ; but the line may be drawn by placing all species 

 with part of the head coloured emerald-green in the latter genus. 



Genus CYGNUS. 



The Swans were included by Linnaeus in the genus Anas, and by Brisson 

 in the genus Anser ; but in 1803 Bechstein, in his ' Ornithologisches 

 Taschenbuch/ ii. p. 404, established the genus Cygnus for their reception. 



The Hooper (C. musicus) is unquestionably the type of the genus. 

 Strange as it appears to us, Linnaeus did not regard the Hooper as 

 specifically distinct from the Mute Swan. He included them both 

 under the name of Anas cygnus, which he divided into two subspecies, 

 Anas cygnus ferus and Anas cygnus mansuetus, of each of which he gives 

 a correct diagnosis. As he distinguished the former as a and the latter as 

 /3, there can be no doubt that he regarded the former as typical. 



The Swans may be distinguished from both the Ducks and the Geese 

 by having the lores bare of feathers. They may further be distinguished 

 from the Ducks by having the front of the tarsus reticulated instead of 

 scutellated, and from the Geese by the shortness of the tarsus, which is 

 not so long as the middle toe. The tail is short and rounded ; the wings 

 are also somewhat rounded, the first four primaries being nearly equal in 

 length, and the longest secondaries are long and broad, and in a state of 

 rest project as far as the tips of the primaries. 



Swans closely resemble Geese in their various changes of plumage, 

 except that the young do not moult in their first autumn, but become 

 much whiter by the abrasion of the grey ends of the feathers. Incubation 

 also lasts longer, from five to almost six weeks. 



There are only seven well-authenticated species of Swan three breeding 

 in the Palaearctic Region, two in the Nearctic, one in South Australia, and 

 one in the southern portions of South America. 



Swans are essentially aquatic birds, frequenting fresh water during the 

 breeding-season, but occasionally visiting the sea-shore in winter. They 

 swim and fly with great ease, but they seldom walk, and never dive. They 

 feed principally on vegetables, but vary their diet with insects and mol- 

 lusks. They build large nests on the ground, and lay several unspotted, 

 almost white, eggs. 



2i 2 



