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Biclieno and a female Zebra, and a male Black-rump 

 and a female Zebra. The pairs were so arranged as 

 to be out of sight of each other, but not out of 

 hearing. All four pairs built nests in cocoanuts, and 

 eggs were continually being laid by the two hen Zebra 

 Finches, but not by the hen Double-banded Finches. 

 These eggs were generally in batches of four or five 

 and both birds of each pair sat on them in turn. For 

 many months, however, the eggs all proved sterile. 

 At length, on examining a batch of eggs by holding 

 them towards the light, I was pleased to find that they 

 showed signs of embryos. These were from the 

 cage with the male Bicheno and hen Zebra. Before 

 they could be hatched, however, the hen Zebra 

 unfortunately died. I put in another hen Zebra but 

 no more fertile eggs appeared, although I kept all 

 four pairs going for several months longer. As all the 

 birds concerned were constantly exchanging call 

 notes I thought perhaps that this interfered with the 

 proper mating of the birds. I accordingly removed 

 three of the pairs, and kept only a male Black-rumped 

 Finch and a hen Zebra in a cage, no other Zebra or 

 Double-banded Finch being within sight or hearing. 

 Again there were many eggs, ])ut none fertile. Later on 

 I replaced the male Black-rump by a male Bicheno. 

 The first eggs were sterile, but soon several fertile 

 ones appeared. However, as long as they were in the 

 cage the birds always failed to hatch them, though 

 several times the dead birds in the eggs seemed 

 large enough to hatch. I then turned the pair into a 

 large aviary which also contained several other 

 finches. They speedily built a nest in a German 

 canary cage, and four eggs were laid. Only one egg 

 however proved fertile, but this was duly hatched on 

 October 14th, 1903. On April 12th, 1904, another 

 hybrid was hatched out, and again on July 14th, 1904, 

 still another, but strange to say in all three cases 



