1917-] Br ceding 'habits of the Cuckoo. 197 



Variation of four eggs taken in 1878 : — 



•81" X '63", weight 220 grammes. 

 •82"x-65" „ 230 



(iv.) Example No. 61.— Female No. 23.— Type "White- 

 throat." Colour green, clouded with grev; and with 

 some small black markings. 



Variation of two eggs taken in 1878 and 1881 : — 



•80" X •fiG", weight 230 grammes. 

 •88"x^64." „ 230 



The remarks made above seem to apply equally to these 

 two examples, and other instances in which the differences 

 appear extraordinarily slight could be adduced. 



Now even if we admit that verbal description may be 

 inadequate to describe the small but distinct variations in 

 egg-coloration, it still seems clear that eggs, such as the 

 above, which Dr. Rey definitely assigns to different females, 

 did not differ so much as those variations met with in 

 clutches of other species. 



He quotes, however, one interesting example (No. 11 — 

 Female No. 28) in the eggs of which the shape and shell- 

 substance were abnormal, probably owing to a defect in the 

 oviduct, and to this reference will be made later. 



Finally, he quotes a case of two eggs, found by himself 

 and his son, with an intervening period of fifteen years, which 

 he describes as being so identical that no oologist could 

 doubt the fact of their having been laid by the same bird ! 

 I am inclined to think, however, that this occurrence rather 

 staggered him, for he appears to suggest that they may 

 have been laid by a mother and daughter, the latter having 

 inherited the egg-coloration. 



It seems, then, that Dr. Eey^s claim to be able to assign 

 each egg to a specific female is, to say the least of it, ques- 

 tionable in many cases, and yet if this cannot be upheld, 

 the strongest evidence he has in support of his conclusions 

 Nos. 6, 7, 9, 10, 11, 12, and 13, vanishes, and any certainty 

 regarding them is greatly decreased. 



