336 
vescente fasciatis ; cauda dorso concolore, distinctius transver- 
sim lineolata ; rectricibus duabus intermediis unicoloribus ; 
reliquis fasciis duabus latis nigris, ante apicem notatis, omnibus 
subtus pallidioribus ; rostro et pedibus nigris ; wide obscure 
grisea. 
Long. tot. circa, 28; rost. a nar. 13!"; al. 12’; caud. 10"; 
tars. 5!" 2!"; dig. med. 2"; dig. int. 13"; dig. ext. 1" 5'"; pollic. 7. 
5. On some Hysrip Ducks. By ALFrrep Newron, M.A., 
F.Z.S. 
5 (Aves, Pl. CLXVII., CLXVIII.) 
The phznomena of Hybridism are in themselves so interesting, 
and at present so little understood, that I venture to call attention 
to some examples illustrating the subject, which I now have the 
honour of exhibiting to the Society, and to make some observations 
thereon. 
The proverbial fidelity of Pigeons, when once mated, has been 
found a matter of much convenience to at least one gentleman who 
has studied the great question of the “Origin of Species,” by en- 
abling him to experimentalize, comparatively without difficulty, on 
the different races, breeds, or varieties which can be produced from 
one common stock *. I would remark, on the other hand, that the 
tendency, under certain circumstances, to polygamy which obtains 
among many of the Ducks, combined with their natural salacity, is 
such as to render that family, perhaps, the one of all others in which 
experiments on hybridism can be the most easily tried. 
The frequent occurrence of hybrids among the Anatide has already 
attracted the notice of ornithologists, and among them of one of the 
most distinguished European naturalists, M. de Selys-Longchamps, 
who in 1845 enumerated no less than twenty-five different crosses 
produced between various members of this family, and who eleven 
years later was enabled to raise the number to forty-four +. Others 
have also been recorded. 
Although by far the greater proportion of these crosses take place 
in a state of partial domestication, there can be, I think, no doubt 
that some occur among birds in a wild state. As an instance I may 
mention one, the offspring of which has been described, it is true, as 
a distinct and good species under the various names of Anas mer- 
goides, Mergus anatarius, or Clangula angustirostris, which I can- 
not but join such high authorities as Naumann, Hartlaub, Baldamus, 
Von Homeyer, Blasius, and De Selys in considering to be the pro- 
duce of Anas clangula and Mergus albellus, though Kjerbodlling, 
Cabanis, Reichenbach and Hennecke are of a contrary opinion. 
* C. Darwin, ‘On the Origin of Species,’ London, 1859, p. 42. 
+ Edm. de Selys-Longchamps, “ Récapitulation des Hybrides observés dans 
la Famille des Anatidées,” Bulletins del'Acad. Roy. de Bruxelles, tom. xii. no. 10 
(1845) ; and“ Additions 4 la Récapitulation,” &c., Bull. de l’Acad. Roy. de Bel- 
gique, tom. xxiii. no. 7 (1856). ° 
