HYBRIDISM AMONG COCKATOOS. 9 



that the cockatoos would not give proper attention to incuba- 

 tion, placed theui under a hen, but the egg-shell proved to be 

 too delicate, and the eggs were soon broken. In 1909 another 

 two eggs were laid, and they Avere placed under a pigeon ; 

 but the pigeons were not disposed to take any notice of them, 

 aud they were almost immediately smashed. In 1910 two 

 en-g-s were likewise laid in the middle of August, and the 

 cockatoos Avere allowed to take charge of them. The male- 

 and female-birds took turns in incubation, and in due time 

 one egg hatched, while the other was addled. Colonel AVales 

 informs me that he did not take special note of the period of 

 incubation, but he believes that it was about twenty -one days. 

 The egg which did not hatch was thrown away without being- 

 examined. In 1911 the female-bird dropped two eggs from 

 her perch and they were smashed. In 1912 two eggs were 

 laid and sat upon by the birds, but they were addled. In 

 1913 three eggs were laid, and after incubation by the 

 cockatoos one egg hatched while the other two were addled. 

 Thus in three separate years, 1910, 1912, 1913, out of 

 seven eggs laid in all, only two hatched, and the hybrids 

 thus arising form the subject of the present observations. It 

 cannot be said for certain whether the eggs failed to hatch 

 through non-fertilisation, or through the death of the embryos 

 owing to constitutional weakness. It is clear that the pro- 

 portion of eggs which hatched (two out of seven) was low, 

 and it Avould appear probable that this was due to the fact 

 that the male- and female-birds were of different species. 



The male-bird (PI. II, A), was a fine specimen of C. 

 galerita; and it may be useful to quote here the description 

 of the species given in the British Museum Catalogue.^ 



"Adult. — White, crest sulphur-yellow; base of the inner 

 web of quills and tail-feathers pale sulphurryellow, like the 

 base of the feathers of the head and neck ; ear-coverts some- 

 times tinged with sulphur-yellow ; naked skin round the eyes 

 white; iris dark-brown; bill black; feet blackish. Total 



' ' Catalogue of the Bii-ds in the British Museum,' vol. xx, p. 117. 



