A COMMENTARY ON NOS. VII. AND VIII. OF " THE NATURALIST." 289 



afforded by the ordinary limitation of forms within a restricted range of the 

 vertical series. Unless, indeed, we admit the possibility, and even the proba- 

 bility, of the absolute similitude of distinct species, or, in other words, of races 

 not descended from a common parentage, the question arises, Where are we to 

 fix the maximum of approximation of what are allowed to be distinct species ? 

 I think, however, that there is much reason to suspect that many closely-allied 

 original races have blended, their mixed offspring becoming mutually fertile in 

 proportion to the amount of affinity subsisting between the parents. The com- 

 parative sterility of mules betwixt the Horse and Ass, or between the Pheasant 

 and Fowl, I deem to be very far from deciding this important question. Let the 

 hybrid progeny of the Whitebreasted and Yellowbreasted Martins (between 

 which animals, I am informed by an anatomist of the highest authority, that 

 osteological distinctions exist), of the Mouflon and Argali Sheep, of the Mealy 

 and Rose Linnets of Britain, or the true Phasianus torquatm and Pk. Colchicus, 

 or even of the Japanese and Indian Peafowl, be brought to the test, and I think 

 that the result would then be more satisfactory. Surely it does not follow, that 

 because the male progeny of the Goldfinch and Canary should be mutually un- 

 prolific, the same would obtain with the mixed breed of Carduelis elegans and 

 C. caniceps, or with the hybrid offspring of the three closely-allied Jays of 

 Europe, Asia-Minor, and Japan. I do not say that even these would naturally 

 intermingle, if wild in the same locality ; but, as species approach so very nearly 

 as these do, there is of course no reason why some should not even more closely 

 resemble. The Greater and Common European Bullfinches accord exactly to a 

 feather, and as intimately in relative proportions; but they differ greatly in 

 size,* and intermediate examples have never been met with. The female of the 

 Japanese Bullfinch can only be told from that of Britain by the discordancy of 

 a single feather, the smallest wing tertiary, which in both the European species 

 is invariably tinged with red, in the females as well as in the males ; a character 

 not observable in that of Japan, which is besides, as can be seen only on com- 

 paring them together, of a rather different shade of brown upon the back. The 

 Himmalayan Pyrrhula erythrocephala, inhabiting an intermediate region, though 

 true to the type, is manifestly and obviously distinct, as the warmest advocates 

 for climatal variation will readily allow. To give one or two more instances. 

 Otus brachyotus of Europe and North America, when many specimens from 

 both continents are seen together, is observed to be constantly of a more rufous 



* For instance, the wing of the Great Bullfinch (of course I allude not to the Cory thus enuclealor, 

 which has been improperly ranked in Pyrrhula) measures 3£ inches, that of the Common species 

 3 inches ; the tail of the former is 3 inches long, of the latter 2§ inches ; and the difference in 

 bulk corresponds to that of the linear dimensions. I have measured three specimens of the Great 

 Bullfinch, which agree precisely with one another. 



