MARCH 63 



into play a most serviceable instrument for picking 

 up creeping things. The tip is horny and armed with 

 a few bristles; the bone of the tongue is prolonged 

 backwards in two branches, reaching round the back 

 and over the top of the head, and meeting again in the 

 cavity of the right nostril, where they are fixed. In- 

 side the bow thus formed runs a strip of muscle, which, 

 when it is contracted, bends the bow and extrudes the 

 tongue. Then, beneath each ear is a gland discharg- 

 ing a glutinous secretion into the trough of the lower 

 mandible, where the tongue lies when at rest, so 

 that the bird is able to catch the smallest creeping 

 thing. 



Admirable as is the tongue of the green woodpecker 

 as an example of consummate adaptation of structure 

 to requirements, it is by no means the only organ 

 which has been modified to suit this bird's peculiar 

 mode of getting a livelihood. The foot is what is 

 known as ' zygodactyle ' that is, arranged with two 

 toes in front and two behind, and the tail-coverts are 

 stiff, with sharp points, so as to act as a support in 

 climbing. Then the breast-bone has been pared away 

 in a remarkable manner, so as to clear the tree-trunk 

 in ascending, for the yaffle never ' climbs down.' When 

 he gets as high on a tree as he thinks there is any 

 need for, he either begins operations again at the base, 

 or flies off in a jerky, undulating way to another. The 

 pectoral muscles are wanting in the depth and power 

 necessary for prolonged flight, which matters little to 

 a bird like the yaffle, of exclusively silvan habits, 



