129 [ Vol. xl. 
Netherlands,” and special reference is made to investi- 
gations by Krukenberg, who found them to be covered by 
a green pigment called biliprasm (green) suffused with 
oorhodene (reddish brown) in the uppermost glutinous layer, 
and which gives the surface of the shell a greenish colour 
with olive longitudinal markings, one of the characteristics 
in the eggs of this group. In the cyanic eggs already 
mentioned, Lechner considers biliprasm is either wholly 
absent or occurs in very small quantities, oocyan (blue) being 
present only as a surface-colour. This I have found to 
hold good. 
The results of the examination of egg-shell mammilla by 
W. von Nathusius are so interesting that I give the quotation 
in full from the same work :— 
The result of the examination of the egg-shell mammille 
of corone, cornix, and corone x cornia, by W. von Nathusius, 
gives good grounds for the suspicion that bastardization is _ 
of influence on the size of the mammillee, and that of the 
eggs of corone X coraa the size lies between those of the two 
species. Eggs obtained by Baron R. Snouckaert van Schau- 
berg in the province of Zealand, and now in the Lechner 
collection, claim to be well characterized bastard eggs, 
which he says conform with reports received from abroad 
respecting similar eggs. These offer no external points of 
difference from pure corone and cornia eggs. 
Newton, in referring to the question of the grain of egg- 
shells in the ‘ Dictionary of Birds’ (p. 189), claims that 
differences are observable in the eggs of corone and corniz, 
which he considers are only forms of the same dimorphic 
species, calling attention to what he considers still more 
wonderful, that the eggs of the hybrids between the two 
forms are recognizable under the microscope by the structure 
of the shell; while yet most extraordinary is the general 
conclusion that the eggs laid by a bird mated with a male 
of different species, is recognizable from one laid by the 
same bird when paired with a male of her own. 
I have examined with a low-power microscope a number 
of eggs of corone and corniv, and find there is a slight 
