What is a Species ? 237 



the conclusions arrived at by the writer. There can be no 

 possible doubt of the perfect fertility of the half-bred 

 Amhersts. Mated with the pure Amherst, three-quarter pure- 

 bred birds are the result ; these show very Httle trace of the 

 Golden species. The half-bred Gold and Amherst are equally 

 fertile when mated with one another, and an intermediate 

 breed may be perpetuated, which possesses the united beauties 

 of both parent species, and be perfectly permanent in its 

 characters. 



The perpetuation of permanent races produced by the 

 union of two perfectly distinct species is well known to all 

 who do not wilfully shut their eyes to those facts which do 

 not square with their theories. The late Mr. E. Blyth, a most 

 accurate observer, and whose knowledge of species was unsur- 

 passed, informed me that over a large extent of India no other 

 domestic goose is known except the cross between the Chinese 

 species {Anser cygnoides), and the domesticated variety of the 

 grejr-lag goose {Anser fer us). 



In the case of the true pheasants, P. colchicus, P. torquatus, 

 and P. versicolor, every variety of interbreeding takes place, 

 and the intermediate forms can be perpetuated as may be 

 desired ; or, as was originally the case with the P. versicolor 

 in this country, the pure breed can be established from a 

 single individual. 



Most naturalists maintain that these three pheasants are 

 perfectly good species ; but what is the test of a species ? 

 For my own part, I am sufficiently heterodox in my behef to 

 regard all the true restricted pheasants, such as P. colcJiicus, 

 versicolor, torquatus, shaivii, mongolicus, elegans, &c., as mere 

 geographical variations of one type, capable of breeding 

 together and perpetuating any cross that it may please 

 experimenters to produce ; and in the same manner the two 

 species of the genus Thaumalea, namely, the Gold and 

 Amherst pheasants, may be regarded as geographical races 

 capable of yielding a permanent race intermediate between 

 the two. 



