234 A HISTORY OF BIRDS 



mouth are spotted with black, while in the Bearded Titmouse 

 the inside of the mouth is of a bright cornelian red, surrounded 

 by a band of yellow, and relieved by a double row of white, 

 glistening, tooth-like conical processes resembling' palatal teeth. 

 The nestling of the Red-tailed Weaver-finch of Samoa has a red 

 wattle at the gape. But the high-water mark of ornament in 

 this matter has been reached by the young of the Gouldian 

 Weaver-finch. Here, the angle of the mouth is ornamented with 

 three bead-like bodies of a brilliant opalescent emerald green 

 and blue, while the roof of the mouth is marked with five black 

 spots perfectly symmetrically disposed, and a black bar crosses 

 the tongue. The young of the Crimson-eared Waxbill or 

 " Cordon-bleu " and of the Parrot-finches are similarly marked. 

 These peculiar markings have a special purpose, inasmuch as 

 the young so ornamented are invariably hatched in places where 

 there is but little light, so that the parents use these markings 

 as guides to the mouth when feeding. This interpretation I 

 owe to my friend Dr. A. G. Butler. 



