4432 THE ZooLocisT—May, 1875. 
analogy. Hybridism is not uncommon in the animal kingdom as 
an exceptional occurrence; but I know of no other instance of 
such a constant unhesitating union of two so-called species as is 
here exhibited. Whenever these two forms associate together in 
spring they seem habitually to pair, showing no special preference 
for partners of their own colour. And it is impossible, with such 
information as we have before us, not to question the specific value 
of these two reputedly distinct forms: surely they must be mere races 
of the same species. The mongrels seem to breed as freely as their 
parents, and their reproductive organs exhibit no deterioration. Is 
this a case, then, where a physiological difficulty to Darwinism is 
surmounted ? or is it a mere case of the intermingling of races or 
varieties, the progeny of which mixture reverts to the one form or 
the other of the parents? The black individual mentioned by Mr. 
Hepburn in the brood of two gray birds or hooded crows would 
appear to point to such being the fact. The only character dis- 
tinguishing the hooded from the carrion crow is the gray colour of 
the back and belly of the former; in form, size and proportions 
they perfectly agree; the habits are very similar, and the nest and 
eggs are undistinguishable. In fact, it would seem that the hooded 
crow is a northern, the carrion crow a southern race of one and the 
same species. And that at the boundary line, when the two races 
meet, they pair freely together and breed without the least reluc- 
tance. The northern form migrates in winter southwards, and 
considerably overlaps the boundary line, and flits again in spring, 
a few individuals occasionally remaining and pairing with their 
southern kindred, as, for instance, the Scarborough example 
mentioned by Yarrell. A solitary instance of the same kind in 
Northumberland came to my knowledge some years ago. There is 
nothing extraordinary in this; for many species of birds of par- 
tially migratory habits do the same; that is, while some indi- 
viduals remain in the country to breed, others learn to do so 
in their northern haunts. The woodcock is a notable example 
of this fact; the crossbill, shorteared owl, siskin, lark, golden- 
crested wren, ruff, and many others do so likewise.”—Hancock, 
p- 33. 
In my opinion the hooded and carrion crows are distinct species, 
as their notes and habits are different. Mr. Selby says of the 
former, “ Their note is harsh, rather shriller than that of the carrion 
crow, and easily distinguished from it.” I can confirm the truth 
é 
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