[34] 



CiKulus canortcs is tending to break up into a number of sub-species, 

 each with its own particular habits in respect of selecting a foster 

 parent" (p. 363). 



It is not my intention in the present paper to criticise this conclusion on 

 the evidence submitted in Mr Latter's paper, further than to remark that there 

 appears to be an arithmetical slip in his determination of the significance of 

 the difference between the mean lengths of the total Cuckoo eggs treated of 

 and the mean length for the " Sedge-warbler-cuckoo " group. Besides, the 

 standard deviation of sampling used is not that of the difference between a 

 general mean and a local mean, which is the difference Latter considers. 

 Even when the correct formula is used it does not render distinctly significant 

 the difference in the " Sedge- warbler-cuckoo." 



The proposition here submitted, based upon the coloration of the Cuckoo's 

 egg, is that the assumed habit on the part of the Cuckoo of adhering to a 

 particular species of foster bird is not in general agreement with fact. 

 Further, we have here confirmed two generally recognised facts : — 



(1) A considerable variability of colour in Cuckoos' eggs in general ; 



(2) A marked uniformity of colour of the egg of the individual bird. 



An examination of the 300 Cuckoo eggs in the Fenton collection reveals 

 the fact that in this species there is a wide range of variation as regards egg 

 coloration. This agrees with the observation of other investigators, e.g. 

 Newton (4), Baldamus (1), Herrick (2). Herrick states : " When taken at 

 random they are very variable in colour, ranging from blue, or blue-green, 

 through speckled blue, brown, mottled or marbled brown, and grey to nearly 

 plain white." There is also general agreement upon the question of the 

 uniformity in coloration of the eggs of the individual Cuckoo. Newton 

 writes : " It is unquestionable that whatever variation there may be among 

 the eggs laid by different individuals of the same species, there is a strong 

 family likeness between the eggs laid by the same individual, even at the 

 interval of many years" (D. of B., p. 123). Herrick states: "The same 

 Cuckoo always lays eggs of similar colour, colour pattern, size and form in a 

 single season, and probably during life. According to Baldamus this has 

 been proved to hold true in one case for three successive years. If two or 

 three Cuckoos' eggs are found in the same nest, they are supposed to belong 

 to different birds, and no case is known where such eggs were similarly 

 coloured." 



An examination of the Cuckoos' eggs in the Fenton Collection, grouped 

 according to locality and date of taking, shows the presence, in numerous 

 instances, of sets of eggs of strikingly uniform coloration. No other 



