598 MR. J. LEWIS BONHOTE ON HYBRID DUCKS. [May 25, 



The number of departures during the same period, by death 

 and removals, was 161. 



Amongst the additions special attention may be directed 

 to:— 



One Burchell's Zebra {Equus hurchelli) S, fi'om S. Africa, 

 presented by F. A. R. Zurcher, Esq., on April 1st. 



One Eland {Taurotragus oryx) cS , born in the Menagerie on 

 April 3rd. 



One Cape Ant-bear {Orycteropus capensis), from S. Africa, 

 purchased on April 17th. 



One Black-fronted Bulbul {PycnonoUis nigricans); one Red- 

 capped Lark {Tephrocorys cinerea), presented ; and two Levaillant's 

 Bai-bets {TrachyphonvjS cafer), new to the Collection, one Martial 

 Hawk-Eagle {Spizaetus bellicosus), deposited with other S. African 

 Birds by Major Boyd Horsbrugh, F.Z.S., on April 15th. 



Mr. J. Lewis Bonhote exhibited an example of a tetragen duck, 

 which he had bred in his Aviaries, containing Wild Duck 

 (Anas boschas), Spotbill (Anas poecilorhyncha), Australian Duck 

 (Anas superciliosa), and Pintail [Dafila acuta). This bird was of 

 the Eg generation, i. e., it had been bred from brother and sister 

 and was remarkable in that, to all outwai-d appearances, it was 

 almost indistinguishable from a pure bred Wild Mallard. 

 According to Mendel's Law it was to be expected in theory that 

 such a bird should appear, but in practice the chance of all the 

 Mallard characters appearing in any one individual was very 

 remote, and the fact that they had all appeared in this bird was a 

 striking confirmation of the truth of Mendel's Law even in a veiy 

 complicated case. 



The only difference to be noted between this bird and the pure- 

 bred Mallard was the rather more defined and Pintail-like vermi- 

 culations to the flank-feathers. 



Mr. Bonhote also exhibited a pair of pentagens of the F„ 

 generation. These contained the blood of the following species^ 

 A7ias boschas, A. poecilorhyncha, A. s^iperciliosa, A. melleri, and 

 Dafila acuta. As yet they showed no tendency to infertility, but 

 on the contrary proved more fertile than several less complicated 

 crosses. The matter had become too much involved to di-aw any 

 deductions from their plumage, but it would be noticed that the 

 Mallard seemed to predominate. They w^ere interesting, however, 

 as showing to what extent cross-breeding could be carried among 

 certain species, the hybrids proving fertile to at least the 4th 

 generation since the last cross with a pure species. 



Many hybrids, as was well known, were unfertile, but with those 

 that proved fertile in the first generation, infertility was generally 

 reached in the 3rd generation (F^) — that is to say the 3rd 

 generation from the last cross with a pure species ; in some cases, 



