THE EGG OF CUCULUS CANOEUS. 
AN ENQUIRY INTO THE DIMENSIONS OF THE CUCKOO'S EGG 
AND THE RELATION OF THE VARIATIONS TO THE SIZE 
OF THE EGGS OF THE FOSTER-PARENT, WITH NOTES ON 
COLORATION, &c. 
By OSWALD H. LATTER. 
[Received October 2, 1901.] 
Introductory. 
The present paper is the outcome of an examination of 44 Cuckoo's eggs in 
the collections at the Charterhouse Museum. The results of this preliminary 
investigation were communicated to the Congress of South Eastern Natural 
History Associations, held in the summer of 1901 at Haslemere, under the 
auspices of the Haslemere Microscope and Natural History Society, of which I 
have the honour to be a member. Finding that 44 was far too small a number 
of eggs for my purpose I extended the series of measurements by including a 
large number obtained at the British Museum of Natural History, S. Kensington, 
and I may here take the opportunity of expressing my thanks to the Director, 
Prof. Ray Lankester, and Mr Ogilvie Grant for granting me permission to examine 
the fine series under their care, and also to Mr Baldwin Young of Sheffield, who 
kindly supplied measurements of six Cuckoo's eggs in his possession. The total 
number of Cuckoo's eggs measured and included in this enquiry is 243, of which 
223 were known to have been deposited in the nests of 42 different species of 
birds, while the foster-parents of the remaining 20 were not ascertainable ; these 
20 have not been excluded from the calculations, for their effect upon the value 
of mean length and breadth is practically negligible. In dealing with coloration, 
a further 45 which were not accessible for purposes of measurement have been 
included, bringing the total to 288. All measurements were taken with sliding 
