634 Letters, Extracts, and Notes. [Ibis, 



of our knowledge of the subject. Although the species 

 mentioned are stated to breed in England, we are not 

 informed whether the cases referred to actually took place 

 in the British Isles. In five or six cases the records are 

 apparently drawn from Continental sources, and in some 

 instances refer to subspecific forms which do not breed with 

 us at all. Altogether 58 species of fosterers are mentioned 

 in 'The Ibis' list, but though this number is approximately 

 correct, great alterations would have to be made before 

 it could be taken as accurately representing the status of 

 British foster-parents. For example, the Marsh-Warbler is 

 included among the species commonly selected as fosterers, 

 although only about half a dozen instances are known in 

 which this event has taken place in England. The Song- 

 Thrush is rightly classed among the occasional fosterers, 

 but I am aware of at least eleven instances in which 

 Cuckoos' eggs have been found in the nests of this species. 

 I shall be glad of any reliable evidence that Cuckoos' eggs 

 have been found in the nests of Magpie, Jay, Stock-Dove, 

 Turtle-Dove, or Little Grebe anywhere in the British Isles, 

 and further information would also be most acceptable in 

 the case of the Goldfinch, Pied Flycatcher, Tree-Creeper, 

 and Jackdaw. On the other hand, the omission from the 

 list of Reed-Bunting, Cirl Bunting, Ring-Ouzel, and Dart- 

 ford Warbler, all of which have been proved to act as 

 fosterers in the British Isles, is inexplicable. 



Bare lists of foster-parents at the present day are practi- 

 cally useless, and have no scientific value unless evidence is 

 given in the case of all species previously unrecorded or 

 included on dubious authority. 



I venture to think that the whole argument on p. 213 is 

 based on a misunderstanding. When Dr. Rey wrote that 

 there is no proof that a fresh Cuckoo's egg is laid on the 

 day it is found, and that it may possibly have been laid one 

 or several days previously, he merely implied that the egg 

 might have been lying in the nest for two or three days 

 before its discovery. There is no reason to believe that he 

 thought the Cuckoo stored its eggs in a larder, either on 



