(Dffidal dDrgan oi the .^ustvakeiait ODrnithoIogist©' Euion. 



" Bir^s of a fcatbcr." 



Vol. VIII.] 1ST JULY, 1908. [Part 1. 



A Synopsis of the Genera and Species of Cygninae. 



By Harry C. Oberholser, Washington (U.S.A.) 



The few species of Swans known to science form a comparatively 

 well-defined group, usually, and proba])ly rightly, considered of sub- 

 family rank in the great family Anatidce. The genus Coscoroba, 

 Reichenbach, by some authors associated with the Cygnince, is 

 undoubtedly a Duck, and belongs among the Anaiince, although it 

 forms to some extent a transition to the Swans. 



With regard to the genera to be recognized in the sub-family 

 Cygnince there has been considerable difference of opinion, but 

 most authors admit only two^not counting, of course, the recently 

 described ArchcBocycnus, De Vis.* Including this, there seem to 

 be, however, five groups that are clearly of generic rank, and that 

 rest upon characters quite as good as those adduced to separate 

 the two current genera. The genus Palceocycmis (Stejneger), 

 founded on the gigantic Cygnus falconeri of Parker, from Malta, 

 seems to be undoubtedly valid, as this bird conspicuously differs 

 from true Cygnus in its relatively short thigh bone, long 

 tarsometatarsus, and in the very thick, abbreviated phalanges of 

 the toes, showing thus no little vergence toward the Anserince. 

 The separation of Cygnus melancoryphus as a generic type,t 

 however, is not maintainable, since this species is strictly congeneric 

 with those of Cygnus proper. Although the diagnostic points 

 given by Dr. Stejneger for the separation of Cygnus from Olor% are 

 all insufficient, there exist, neveitheless, excellent characters, both 

 external and anatomical — particularly the latter — which, it is 

 hoped, may now finally establish these much-abused groups. The 

 genus Olor differs from Cygnus in lacking any knob, or tubercle, at 

 the base of the culmen, in having a more or less evident bronchial 

 dilatation, and in having the trachea looped and entering the 

 sternum. 



A key to the living genera of the sub-family sets forth their 

 salient characters in more grcnphic form : — 



a.— Tail longer than middle toe with claw ; tertials and 

 scapulars smooth. 



* Ann. Queensl. Mus., No. 6, 1905, p. il. 



t Stejneger, Proc. U.S. Nat. Mus., v., 1882, pp. 183, 185. 



JProc. U.S. Nat. Mus., v., 1S82, p. 183. 



