Vol. xxxvi.] 24 



characters furnished by the eggs, are " adaptive '^ characters, 

 and must be used with caution. Much more reliable are 

 the data furnished by the muscles, skeleton, and embryo. 



In the case of the Grebes and Divers, to which reference 

 has been made, it is to be noted that, according to the 

 evidence derived from the eggs, these two belong to widely 

 different orders. Yet the evidence furnished by their 

 iauatomy seems to show, fairly conclusively, that they are 

 derivatives of a common stock, and not that their close 

 likeness is due to parallel development, such as obtains 

 between the Owls and the Accipitres. There can be no 

 doubt but that the Owls are Coraciiform birds, while the 

 Accipitres are of a Ciconiiform stock. 



With regard to the coloration of white eggs, Mr. Jourdain 

 holds that eggs are white because of the atrophy of the 

 pigment-glands of the oviduct. That is true, but it does not 

 go far enough. I think the whiteness of such shells — 

 which are usually laid in holes — is to be attributed to the 

 action of Natural Selection which has eliminated those birds 

 which, breeding in holes, laid coloured eggs. I fail to see 

 otherwise why Thrushes' eggs are coloured, for so far as 

 I know, this coloration confers no benefit on the species. 



Without doubt Mr. Jourdain has raised some interesting 

 points in his endeavour to demonstrate a direct relationship 

 between the coloration of the egg and the life-history of 

 the bird. 



Mr. E. C. Stuart Baker : I would preface what I have 

 to say to-night by stating that I am firmly of opinion that 

 Oology can be of the greatest use as an aid to classification, 

 but I think that it must be worked in moderation, as should 

 be every other method by which we differentiate between 

 species, genera, and families. What may be a characteristic 

 of the greatest importance in one case may be of no use 

 whatsoever in another. Oology, I consider, is of less use 

 in determining differences than as a guide which shall lead 

 us to examine more carefully species, genera, or families 

 which show striking anomalies in. the eggs they lay. 



Colour is, of course, only one of the many characteristics 

 of eggs which have to be taken into consideration ; texture. 



