HYBRIDISM AMONG COCKATOOS. 



A Case of Hybridism among Cockatoos. 



By 



Eriieii>t Warren, D.Sc.Loiid. 



With Plate II. 



There has recently occurred an interesting example of 

 hybridism among certain tame cockatoos in Pietermaritzburg, 

 and since the character of hybrids gives some insight into the 

 problems of hereditary transmission it appeared to be desir- 

 able to publish an account of the matter, and the living birds 

 have been studied as carefully as circumstances would permit. 



The cockatoos belong to Lieut. -Colonel A. T. Wales, resident 

 in Pietermaritzburg, who has very kindly allowed me to sketch 

 the birds and have them photographed ; my thanks are also 

 due to his daughter, Mrs. Brown, who, having considerable 

 control over the somewhat wild birds, rendered great assist- 

 ance while they were being photographed. My friend, Dr. 

 Conrad Akerman, was good enough to undertake the photo- 

 graphing, and from the prints of the negatives thus obtained 

 the lithographic plate was prepared. The artist who coloured 

 the plate was provided with a selection of the variously 

 coloured feathers. 



The male-bird is the common sulphur-crested cockatoo, 

 Cacatua galerita [Lath.), and the female is the so- 

 called slender-billed cockatoo, Licmetis nasica {Temm.). 

 The birds were obtained on different occasions at the coast- 

 town of Durban, and were doubtless at the time of purchase 

 recently imported from Australia. 



The birds live in a garden under fairly natural conditions ; 



