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Show 710 REV. DR. GOODACRE ON THE CHINESE GOOSE. [N 10. On the Question of tbe Identity of Species of the Common Domestic and the Chinese Goose. By F. B. GOODACRE, M.D., F.Z.S. [Eeceived September 16, 1879.] Having read long ago, in 'The Origin of Species' (p. 275), about tbe fertility inter se of " hybrids" between the Common Domestic and Chinese Geese, I was induced, when tbe opportunity occurred some few years ago, to commence a series of experiments to verify this alleged fertility, several gentlemen very kindly consenting to assist me in the investigation. The following crosses have been obtained by one or another of us, and some of them in more than one case :-Chinese J with Common 2 produced several Goslings ; a pair of these, out of the same nest, have produced young last year and again this; half-bred eS with both Common $ and Chinese 2 * o n e quarter Chinese and three quarters Common d with both Common $ and Chinese 2 • The number of the Goslings in proportion to that of the eggs lias been small in many, but not in all cases, and is, I think, to be attributed to some accident in our arrangements, and not to any lurking sterility between the two forms. In fact I suspect the two forms themselves, and cross-bred birds of them in any proportions, to be quite as fertile inter se as either of the pure forms by itself. Now the chief interest in the results of these experiments seems to be that half-bred birds of the same nest produced young; for, as a consequence of their doing so, we seem compelled to believe one of two things, either that hybrid birds can be fertile inter se, or that the half-bred birds above mentioned were not hybrids at all, but only mongrels; in other words, that the two forms of Domestic Goose are specifically identical. Most naturalists have hitherto considered them specifically distinct; it is certain they either are or are not; and how is the case to be decided ? The declaration of the most learned naturalists either way cannot settle the point, nor do I see any way of doing so beyond all doubt if we give up that rule, so generally received, that hybrids are infertile inter se, and, of course, we cannot quote that rule as a proof against an apparent exception to itself. Yet the fertility of these cross-bred birds may be taken as good presumptive evidence in favour of identity of species in their parent forms, and is quite sufficient to make us inquire more curiously into the matter, to see what other evidence can be found to incline us to believe in such identity. The advocates of their non-identity would very naturally call our attention to the great difference between them as to general form, colour, and voice, to the peculiar knob on the Chinese bird's head, and to its prolonged season of incubation. Tbe existence of the last of these differences (except in books) I have good reason to deny ; the other differences must be admitted, and something said with reference to each to show |