A COMMENTARY ON NOS. VII. AND VIII. OF THE NATURALIST.” 28^> 
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 torquatus and Ph. Colcliicus^ 
or even of the Japanese and Indian Peafowl, be brought to the test, and I think 
that the result would then be more satisfactor}’. 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 
iaosiiiglb feather, the smallest wing tertiary, which in both the European species 
i|: inY^riably 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 erythrocepliala^ 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 Corytlius enucleator, 
which has been improperly ranked in Fyrrliuld) 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. 
