FALCONIDAE. 



foregoing review of the layers of tiie eggshell, furnish us with the 

 distinguishing features for a classification oi the Falconidae, breeding 

 in the Netherlands into three oological groups, as follows: 

 (7. Layer I = green j 



Pern is. 



, Accipitrinae and Buteo. 

 Layer II = white ) 



b. Layer I = green ) 

 Layer II = white, coloured superficially ) 



c. Layer I = white I falco and 

 Layer II = white, coloured superficially \ Cerchneis. 



If we now regard the character of the colouring and markings of 

 the eggs more closely, it will be noticed at once that in the case 

 of the eggs of Pernis, Falco and Cerchneis this character although not 

 fully corresponding, may nevertheless be jointly placed over against 

 the character of the eggs of the Accipitrinae and Buteo. I do not how- 

 ever wish to omit reference here to the fact that in Accipiter, 

 which genus, as stated above, stands as regards texture of shell 

 nearest to Falco and Cerclineis, the markings frequently bear the 

 character of that genera more than they do that of Buteo '), which 

 fact would be still more striking if the surface of layer II of ylcc//7;YtT 

 were also coloured. 



Where markings occurred in Circus I found them on all the 

 layers fully in conformity as regards their nature with those which 

 occur on layer II in Buteo, namely spots of a faint brownish yellow 

 colour, caused, in my opinion, by oorhodein bleached by gluti- 

 nous mucus. 



') RzEHAK rightly says in his characteristics of nisus-eggs, which isotlier- 

 wise not quite correct (Zeitschrift fiir Oologie, V, p. 47): „Manche Eier sind 

 mit einer lichtbraunen Farbe so gezeichnet. dass sie beim ersten Blicli fur 

 tintninailiis-Eier gehalten werden kotinen." 



