Fulton. — The Long-tailed Cuckoo. 123 



blind(28). Few birds are so easily imposed upon as this, and 

 these Chalcococcyx species, hicidus and 2J^<^gosus, have come 

 to find that they are best perpetuated in nests which are 

 liome-shaped or covered in like that of Gerygone or those of 

 the Australian Bush-wrens or Tits. The eggs which are de- 

 posited in these covered-in nests remain of the original sea- 

 green or olive-gx'een colour, there being no necessity, as the 

 eggs are in comparative darkness, for "protective mimicry" 

 to be established. Now, when we examine the egg of Glial- 

 cococcyx basalts we find that the egg is white, spotted with 

 pinkish red, quite a different type of egg altogether. Campbell 

 says of this point, " It will be observed that the eggs of tlie 

 two little Bronze Cuckoos, plagosus and basalts, are totally 

 dissimilar in colouring, notwithstanding that their respective 

 reputed parents are exactly alike both in colour and size. 

 Both wear coats of glorious green ; the young birds are 

 liardly to be separated m appearance, and the adults are 

 extremely alike in plumage, and it would be of great 

 interest if some of our oologists could explain the 

 apparent anomaly in the coloration of the eggs, for 

 experience teaches us that in nearly every genus the 

 true typical egg of each species is not without character- 

 istic resemblance "(29). Now, the remarkable change 

 m the colouring of this little egg is, I think, easily ex- 

 plained. This bird, as one would expect, lays its eggs more 

 often in open or cup-shaped nests than in closed or domed 

 nests, and the eggs have gradually assumed a speckled colour- 

 ing very nearly approaching in appearance the egg of our 

 Gerygone and many of the smaller Australian birds. In this 

 the Narrow-bill Cuckoo is quite distinct from the other three 

 species of Chalcococcyx, whose eggs, being hidden in domed 

 nests, have not required to assimilate themselves to their 

 surroundings. As regards the dark closed nests of the Com- 

 mon Enghsh Wren, no adaptation of the egg of the Cuckoo 

 to the eggs of the owner has ever been noticpd(87). Many 

 of the European Cuckoos lay eggs which are wonderfully 

 approximate in their colouring to the eggs of those species 

 in whose nests they are deposited ; many are abnormally 

 coloured, and quite unlike the ordinary egg of the Cuckoo, 

 but have been proved to belong to that bird on exammation 

 of the contained embryos(30). Among the Australian birds 

 the Koel lays an egg which much resembles that of the Friar- 

 bird, one of its foster-parents, and the Channel-bill Cuckoo's 

 egg IS very like that of the Hill Crow-Shrike {Strepcra 

 arguta){Sl, 32). Enough has been said to show that much 

 variability may be expected in the eggs of parasitic birds all 

 the world over, and consequently differences in the various 

 specimens of the Kohoperoa need not be considered remark- 



