Family CORVIDAE. 

 (Plates 1—6). 



In this family corax, corone and frugilegus form an oologically 

 closely allied group, from which monedula deviates by the lack of 

 one of the most typical characteristics (v. infra). 



Pica which, like glandarius, stands more by itself, sometimes 

 shows an approach to certain variations of the corax group, some- 

 times to those of monedula. 



Glandarius, especially by the texture of the shell, is farthest 

 removed from the typical Corvine character of which the corax 

 group is the bearer. 



I consider those eggs to be typically coloured ones of corax, 

 corone and frugilegus, showing the above mentioned near kinship, 

 of which the uppermost layer of chalk — as the results of Kruken- 

 berg's investigations give rise for us to assume to be the case — 

 is covered by a green pigment, called biliprasin, while oorhodein 

 occurs diffusedly in the uppermost glutinous layer; this gives to 

 the surface of the shell a green colour (varying in shade according 

 to the percentage of biliprasin mixed with the oocyan), with 

 olive, frequently longitudinal markings. This type is characteristic 

 for the corax group. 



