CUCULUS CANORUS L. 



The colour of the markings is frequently in harmony with the 

 ground colour, i. e. it consists of a shade of the latter, on which 

 is based in the case of many of our canorus-eggs the great resem- 

 blance of the character of the markings to that of the eggs of 

 Motacilla flava. 



With the exception of the bluish green phoenicurus-iype, my 

 investigations showed me that the fundamental layer of lime of 

 canorus-eggs is pure white, and that the more or less greenish 

 tint which many eggs show when light passes through them is 

 therefore not caused by oocyan present in that layer, but that its 

 origin must be sought for in the pigment of the superimposed 

 groundcolour-layer. 



To the aided eye the texture of the shell of canorus-eggs is 

 characterized by the fact that each of the closely united particles 

 of lime is clearly perceptible by itself. 



As regards the pores, it would appear to me that there are 

 two types, viz. one type in which the pores are clearly percept- 

 ible, and another in which they are not conspicuous at all. 



The following distinctive qualities are characteristic of canorus-eggs : 



1. the spots, etc. described above sub b. 



2. the specks referred to under c. 



3. the firmness of the shell (distinctly noticeable during pre- 

 paration). 



4. the comparatively great weight of the shell. 



5. the peculiar texture of the shell. 



6. the tolerably constant shape wich shows a distinct flattening 

 near the point where the greatest longitudinal diameter and the 



