NESTLING BIRDS AND WHAT THEY TEACH 241 



also employed. Thus locomotion is quadrupedal at this stage, 

 the creeping movements of the earlier reptilian phase being 

 used in combination with the more avian fashion as practised 

 by the Parrots. 



As might be expected, the wing while used as a climbing 

 organ presents features not to be found in later development 

 when it has assumed its proper function. 



III. 29 



JThe upper and lower figures represent the under surface of the wings of 

 the nestling and adult Hoatzin ; the middle figure that of a nestling of the 

 Common Fowl (Gallus bankiva). The hand of the nestling Hoatzin is seen 

 to be relatively much longer than in the adult, which has also lost the claws. 



The wing of the nestling fowl shows an arrested development of the outer- 

 most quills, just as in the Hoatzin. (After Pycraft.) 



One of the first things to attract attention in the examina- 

 tion of this wing is the presence of unusually large claws on the 

 thumb and first finger, and the great length of the hand which 

 is conspicuously longer than the forearm (111. 29). The thumb is 

 found to be unusually long, and to extend beyond the level of 



16 



