1160 The Zoologist— April, 1868. 



always some nests of other birds, besides the predominating species, 

 would by their eggs have a great influence over the colouring of the 

 cuckoo's eggs. 



But how then could it be explained that two cuckoo's eggs of 

 entirely different colour and marking can occur in one and tlie 

 same nest ? and yet this fact also has been repeatedly established. 

 I myself found in a nest of Calamoherpe arundinacea, which was 

 placed in a ditch sparingly overgrown with weeds, two cuckoo's eggs, 

 together with three eggs of the above-named bird. Of these cuckoo's 

 eggs one had the type of C. arundinacea, and the other had the type 

 of the eggs of Sylvia hortensis. Two other cuckoo's eggs are lying 

 before me, taken from the nest of a warbler [" grasmucke"], very pro- 

 bably of S. cinerea, of which one has the character of the egg of that 

 bird, the other of the eggs of S. atricapilla. That the two first could 

 not have been laid by the same hen (which, moreover, if it was so 

 would not have removed the difficulties before us) is proved by the 

 precisely similar state of advancement towards hatching in both of 

 them [" bewies das gleiche stadium der bebriitung beider"]. Thus 

 they must have been laid by two hens;* but whichever of the two 

 was laid first, and even if the one bearing the type of the whitethroat's 

 egg was laid in the nest while it was yet empty, the difficulty of 

 explaining the colouring of one or the other, according to the theory 

 of Herr Kunz, still remains undiminished. 



Moreover, cuckoo's eggs are found, although rarely, in such nests as 

 have not yet received any eggs of the owner; in which case the 

 cuckoo is without any pattern of a fixed form of colour for its egg. 



Finally, a direct proof, and quite an independent one, against this 

 theory, is furnished by experience, that one and the same hen cuckoo 

 lays similarly coloured eggs in the nests of different species. How- 

 ever important, on one side, is the proof furnished to us by Herr 

 Braune, the forester, that both eggs of the cuckoo he described had 

 the colouring of the eggs of Hypolais, in whose nest the one was laid, 

 it would have been more important if one could have observed in what 

 nest the second egg (which was cut out of the bird) would have been 

 laid. Meanwhile the following fact will support what has been said. 

 As I observed already at the beginning of this paper, 1 found on the 



* Naumai)n,Thienemann, Deglaud and otbevs assert that sometimes two cuckoo's 

 eggs have been found in oue nest, and nearly all those authors add thereupon that 

 they were in all probability laid by two different lieu birds, and this without taking 

 into account the colouring of these eggs. 



