430 . TEE ZOOLOGIST. 



incubating on the approach of Crows, appear to me to be proof 

 that the incubating from the first egg in this (and also many 

 other) species is a protective habit, which preserves the eggs. 

 This I have previously endeavoured to make clear {cf. ' British 

 BirdB,'vol.iv, pp. 137-45; vol. v, pp. 322-27; vol.vii,pp. 105-14); 

 That selection is close was obvious, for the Crows succeeded 

 in taking Gulls' eggs not infrequently. 



