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Show 1905.] MR. J. LEWIS BONHOTE ON HYBRID DUCKS. 149 Mr. Bonhote first dealt in a general way with the appearance of the various specimens, pointing out how the three parent hybrids between the Mallard, Spotbill, and Pintail tended to divide themselves into two distinct forms-a light and a dark, which differed chiefly in the amount of white. The light forms when bred together produced birds as light or slightly lighter than themselves; a tendency which was confirmed in a still more marked manner in the third generation, so much so, that in a full-plumaged drake the only sign of its parentage was represented by the spotted bill of A. poecilorhyncha and the upturned tail-coverts of the Mallard. It was further pointed out that, as in the case of the Mallard- Spotbill hybrids*, so in the case of the Mallard-Spotbill-Pintail, the drakes in their full plumage showed chiefly signs of the Mallard and Pintail, whereas in the eclipse plumage the Spotbill was largely predominant. Mr. Bonhote then briefly discussed some of the results obtained by hybridisation, after laying stress on the antagonism between Natural Selection and Variation, and how the one tended to keep the species pure and fixed in spite of the innate tendency of every individual to vary, and also pointing out how, in spite of Natural Selection, marked variations were constantly making their appearance among pure species-as, for instance, in the so-called Pavo nigripennis, or in Athene chiaradice, a peculiar form of the Little Owl (which was described from Italy a few years ago), or, again, in the well-known Sabine's Snipe. Whatever might be the actual cause, there could be no denying the fact that hybrids tended to show a considerable amount of variation, exhibiting characteristics which might be very misleading to those who did not know their parentage. As a rule, hybrids, while showing on most parts of their body the characteristics of their parents, exhibited in addition other markings. These last sometimes resembled the characters of other species, but in certain cases showed affinity with no known forms. Further, there was a great tendency to become white, and this last feature was ascribed to weakness, as it tended to increase in each generation that was further removed from the pure wild species. Instances were given where, in certain characters, individual Mallard-Spotbill-Pintail showed resemblances to Teal, Gadwall, Wigeon, etc., and where Mallard-Spotbill-New Zealand crosses showed resemblances to Teal and Pintail. Other specimens were also exhibited, showing patterns and markings that resembled no known species. Mr. Bonhote did not believe these resemblances to be due to reversion, but merely to variation; pointing out that in all probability the progenitors of the existing Anatidfe had a potentiality of variation as great as or even greater than that of their descendants of today, and that our present species showed * P.Z.S. 1902, vol. ii. p. 318. |
