The Woodkewer Family, 
259 
dining room, and, concealed under a piece of furni- 
ture, would continue uttering its evening song for 
an hour or longer at short intervals, and rendering it 
so perfectly that I was greatly surprised to hear it ; 
for a thrush or other songster at the same period of 
life, when attempting to sing, only produces a 
chirping sound. 
The early singing of the oven-bird fledgling is 
important, owing to the fact that the group it 
belongs to comprises the least specialized forms in 
the family. They are strong-legged, square-tailed, 
terrestrial birds, generally able to perch, have 
probing beaks, and build the most perfect mud or 
stick nests, or burrow in the ground. In the 
numerous tree-creeping groups, which seem as 
unrelated to the oven-bird as the woodpecker is to 
the hoopoe, we find a score of wonderfully different 
forms of beak ; but many of them retain the prob- 
ing character, and are actually used to probe in 
rotten wood on trees, and to explore the holes and 
deep crevices in the trunk. We have also seen that 
some of these tree-creepers revert to the ancestral 
habit (if I may so call it) of seeking their food by 
probing in the soil. In others, like Dendrornis, in 
which the beak has lost this character, and is used 
to dig in the wood or to strip off* the bark, it has 
not been highly specialized, and, compared with the 
woodpecker’s beak, is a very imperfect organ, con- 
sidering the purpose for which it is used. Yet, on 
the principle that similar functional requirements 
frequently lead to the development of similar 
structures in animals which are otherwise very 
distinct ” — as we see in the tubular tongue in 
s 2 
