The Zoologist— April, 18438. 116S 



particular nests which in her own district do not exist in sufficient 

 numbers.* 



Thus, lastly, it comes to pass that the two prevailing colours of the 

 cuckoo's eggs are spread over mosl localities, whilst at the same time 

 they also appear almost everywhere, as exceptions, in other nests. 

 They are those of Sylvia cinerea and Motacilla alba. The diffusion 

 of these birds is very extensive, and their dwelling-places for the 

 most part offer to the cuckoo also the requirements of its existence. 

 It is therefore not without signification that one seldom finds in their 

 nests cuckoo's eggs of other colours, but one does frequently find in 

 the nests of other birds cuckoo's eggs of their type.f 



It is asserted that numbers convince. Let any one then look once 

 more at the catalogue of the cuckoo's eggs which are lying before me, 

 and he will find that notwithstanding by far the greater part of them 

 are only from this country, which certainly is a very rich locality, 

 still they do not contradict the views explained above. 



In conclusion, let us separate that which is matter of fact, and con- 

 firmed by experience, from the deductions derived therefrom : thus it 

 is proved by facts, that — 



(1). The cuckoo entrusts its eggs to a great number of species of 



warblers to be hatched by them. 

 (2). Cuckoo's eggs occur of a great variety of colours and markings, 

 such as does not happen in the case of any bird (so far at 

 least as is known up to this time). 

 (3). All, including the most varied colourings of its eggs, find 

 analogous eggs amongst those of its foster-parents, similarly 

 coloured and marked, so that they might easily be mistaken 

 for them. 

 (4). Certain particular colourings appear to predominate in different 

 localities. 



* Perhaps they are such hens, of which Herr S. Prevost in general asserts, " As 

 soon as they have paired, have laid an egii, and made themselves certain of its recep- 

 tion on the part of the chosen foster-parents, they desert their first mate to search for 

 another, which they then likewise forsake as they have forsaken the first. According 

 to his account only the males have a fixed station. It would be important to learn in 

 what localities he had made these observations. (Degland, Orn. Europ. i. p. 169.) 



f With regard to these circumstances I was able to assert at Halberstadt (Nautn-. 

 iii. 2, p. 121) that so rash a conclusion from the exceptions produced by Herr J. Hoff- 

 man has no authority, and that even those exceptions are in support of my views. 

 They were almost all of the colours above pointed out, and had been laid in the nests 

 of Rubecula, Hypolais, Phyllopneuste and Linota cannabiua ! (Naura. i. c. p. 15.) 



