iQi/-] Breeding-habits of the Cuckoo. 213 



such a liigh estimate, and then supports his own theory as 

 to the laying on alternate days by tables, but expressly 

 states, which I consider of importance, that in most cases 

 there is no proof that an egg is laid on the same dap that it is 

 found in the nest, but that it may have been laid from one to 

 several days previously. 



This, incidentally, ratlicr supports the theory that tlie 

 nest is selected after the egg is laid, for, if before, there 

 seems in many cases no reason for the delay. As regards 

 Dr, Rey's tables, it will be sufficient to analyse four to see 

 how he arrives at his conclusions. 



{a) Six eggs of female No. 8 were found as follows : — ■ 

 Two on the 5th of May, one on the 8th of May, aud one 

 on the 10th, 15th, and 16th of May respectively. 



Allowing the two days' laying period, which he considers 

 correct, Dr. Rey suggests these eggs were laid on the 3rd, 

 5th, 7th, 9fch, 11th, and 13th of May. 



{b) He states : — In some twenty cases my son succeeded 

 in establishing the fact that the eggs had actually been laid 

 on the day they were found. Thus, on the 20th of May, 

 1891, he found two Shrikes' nests close to each other, one 

 containing four eggs of that species and the other being 

 empty. The following day the first nest contained two 

 Shrikes' eggs and a Cuckoo's egg of female No. 37. On 

 tlie 23rd of May the second nest contained a Shrike's egg, 

 and also a Cuckoo's egg of the same female. Thus the first 

 egg must have been laid on the 21st and the second on the 

 23rd of May. 



The conclusion is not clear ! 



On both the 27th and 29th of May Dr. Eey found other 

 eggs of this female, and states he was able to establish the 

 fact that a fifth egg, found on the 31st of May, was laid 

 on that day, because the previous day it (the nest) had only 

 contained Shrikes^ ^ffff^- 



Other eggs, attributed to this same female, were found on 

 the 4th, 12th, and 18th of June. 



Now, so far as 1 am aware, in such cases there are no 

 means of telling whether an egg found in a nest has been 



