A THEORY OF BIBBS' NESTS. 253 



Real or apparent Exceptions to the Law stated at 

 page 240. 



The only marked exceptions I have been able to 

 discover are the following : 



1. King crows (Dicrourus). These birds are of a 

 glossy black colour with long forked tails. The sexes 

 present no difference, and they build open nests. This 

 apparent exception may probably be accounted for by 

 the fact that these birds do not need the protection 

 of a less conspicuous colour. They are very pugna- 

 cious, and often attack and drive away crows, hawks, 

 and kites ; and as they are semi-gregarious in their 

 habits, the females are not likely to be attacked while 

 incubating. 



2. Orioles (Qriolidae). The true orioles are very gay 

 birds ; the sexes are, in many Eastern species, either 

 nearly or quite alike, and the nests are open. This 

 is one of the most serious exceptions, but it is one 

 that to some extent proves the rule ; for in this case 

 it has been noticed, that the parent birds display 

 excessive care and solicitude in concealing the nest 

 among thick foliage, and in protecting their offspring 

 by incessant and anxious watching. This indicates 

 that the want of protection consequent on the bright 

 colour of the female makes itself felt, and is obviated 

 by an increased development of the mental faculties. 



3. Ground thrushes (Pittidoo). These elegant and 

 brilliantly-coloured birds are generally alike in both 

 sexes, and build an open 'nest. It is curious, however, 



