224 Brewster on Hehninthophaga leucobronchialis. 



sake of argument, that it is always impaired in such cases — of the 

 original hybrids, would soon be restored by this breeding back 

 into one of the parent stocks, and the descendants would hence 

 stand a good chance of being numerous, while it wovdd certainly 

 require the succession of many generations to wholly eliminate 

 the traces of their mixed ancestry. And if this state of affairs 

 exists in one genus of birds, why may it not be looked for in 

 others? There are some puzzling instances of the occasional 

 cropping out of respective characters among allied but apparently 

 perfectly distinct species which cannot be explained by any of the 

 known laws of geographical variation. The possibilities opened 

 li\ this field are bewildering, but for the present we are safer to 

 lay them aside and apply the direct analogy furnished by the case 

 of the Helminthophagce to a few obviously similar ones. 



Until very recently there was not a single established example 

 of hvbriditv among North American Passeres, and many of our 

 leading ornithologists were incredulous as to its occurence in a 

 state of nature save among the Grouse and some of the Swimming 

 Birds, while no one seems to have considered the possibility of its 

 explaining some of the standard puzzles* that have been handed 

 down to us by Audubon and other of the earlier ornithologists. 

 But Mr. Trotter's hybrid Swallow (described in Vol. Ill, pp. 135, 

 136 of this Bulletin) gave us an undoubted instance, and now we 

 have startling evidence that some of the HelmintJiophag(e\ have 

 been regularly contracting misalliances under the very noses of the 

 scientists who were insisting that such things could not be. Who 

 can say where this entirely irregular state of affairs will be found 

 to end ? Cuvier's Kinglet, with its Vermillion crown-patch bor- 

 dered by black stripes, its black eye-stripe and white iving- 



* From a review in a recent number of " Nature " I learn that Mr. Seebohm in his 

 late work on the Turdidce, forming Vol- V, of the " Catalogue of the Birds of the 

 British Museum," has lately recognized hybridity as accounting for certain obscure 

 Old World species ; but up to the time of placing the present article in the printer's 

 hands I have been unable to obtain a copy of his book or to ascertain the precise 

 nature of his investigations. 



f Mr. Ridgway has lately shown (this Bulletin, Vol. V, p. 237) that Helminthophaga 

 cincinnatiensis, Langdon (originally described in Jour. Cin. Soc. Nat. Hist., July, 1880, 

 pp. 119, 120, PI. VI — description and plate reproduced in this Bulletin, Vol. V, pp. 

 208-210, PI. IV) perfectly combines the characters of Helminthophaga pinus with those 

 of Oporornis formosa. If, as seems highly probable, he is right in considering it a hybrid 

 between these species, it affords another striking example of the tendency of H. pinus 

 to seek alien connections. 



