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Show 454 MR. P. L. SCLATER ON AN AUSTRALIAN DUCK. [May 16, 1879 (on Sept. 24, Oct. 10, Oct. 11, Oct. 20, and Nov. 17, and one in 1880, Jan. 30); singularly enough, all these on dissection turned out to be males. The skin of one of them only was in sufficiently good condition to be worth preservation. I now exhibit it, and a drawing (Plate XXXIII.) taken from it by Mr. Smit. I also exhibit the trachea of four of these individuals, showing a distinct bulla ossea, as is usual in the males of the Anatidae1. Having been in error myself as to m y first identification of these Ducks, I fear I have also led Prof. Newton into an error upon the same subject. In January 1871 I furnished Prof. Newton with what I believed to be specimens (in the flesh) of a male and female Anas castanea that had recently died in the Society's Gardens \ Prof. Newton, trusting to Mr. Baker's determination that the presumed female was really of that sex, read a paper upon these birds before this Society in November of that year, in which he pointed out that the presumed female possessed the extraordinary peculiarity of having a bulla ossea, hitherto only known to occur in the male sex of the Anatidae, and proposed in consequence the new generic term Virago for Anas castanea3. But Prof. Newton having been kind enough to send me up the skins of this presumed pair of birds for examination, I think I may say that there is little doubt that Mr. Baker must have made an error in his determination of the sex of the supposed female, and that that bird is in all probability a male of Anas gibberifrons. This hypothesis is rendered more probable by the existence of the marked difference in the sternum between the two birds which Prof. Newton has pointed out, and by the fact that Mr. Ramsay tells us (Proc. Linn. Soc. N. S.W. iii. p. 154) that he has examined six females of Anas castanea without finding any trace of the bulla, ossea. I fear therefore that the proposed generic term " Virago" will not stand. I have not ascertained female specimens of Anas castanea, and cannot, therefore, say how that sex differs in plumage from A. gibberifrons. But it will be at once seen on comparison that there is a considerable difference in the bills of the two species, that of A. castanea being considerably longer and larger than that of A. gibberifrons, and that the presumed female of A. castanea (the type of Virago) agrees in this respect as well as in ever}* other point with the male of A. gibberifrons. 1 The trachea is very similar to that figured by Prof. Newton, P. Z. S. 1871, p. 650, fig. 4. 2 The male was purchased June 15, 1870, and died Jan. 9, 1871; the presumed female arrived May 11, 1865, and died Jan. 7, 1871. 3 See P. Z. S. 1871, p. 650. |
