log 



Nest No. III. 



June 15th July 3rd 18 days 



June 18th — disappeared 



June 20th July 5th 16 days 



June 22ud July 6th 15 days 



Thus of the eleven eggs observed, the period of in- 

 cubation lasted 14 days in one instance and i8 days in 

 another, while the incubation of three occupied 15 

 days, three took 16 days and three 17 days. 



Another important problem on which the avicul- 

 turist should be able to throw some light is the cause 

 of sexual dimorphism in birds. In some species the 

 cock and hen resemble one another so closely that it 

 is impossible to distinguish one from the other by 

 their outward appearance, while in others as, for 

 example, in the New Guinea Eclectus (^Eclectus poly- 

 chloriis) the two sexes differ so greatly that ornitholo- 

 gists at one time took them for different species. How 

 are we to account for this sexual dimorphism ? 



Mr. Wallace, it will be remembered, asserts that 

 the comparatively dull colouring of the female \n 

 sexually dimorphic species is due to her greater need 



