292 SUMMER. 



back are yellow, but still with a slight trace of brown. 

 The under parts are yellowish grey, with a shade of 

 purplish green ; the quills are yellow and grey with 

 dusky bases almost black ; and the tail is barred with 

 dull green and brown. The rump is very stout and 

 muscular ; the feathers of the tail are concave on the 

 under side ; they are very firm, and strong and elastic 

 at the points ; and as the muscular structure of the 

 rump enables the bird to press them downwards with 

 great force, they answer many of the purposes of a third 

 foot. The legs are short ; but both they and the toes 

 are very thick and strongly articulated; and the claws 

 are very firm and strong, compressed at the sides, 

 much hooked, sharp at the points, and of a deep 

 black. The bird is thus remarkably well adapted 

 for supporting itself upon the branch of a tree, even 

 though comparatively smooth, in a vertical position ; 

 though only when the head is uppermost. In that 

 position, the tail acts as a strut or prop, and sus- 

 tains the weight; whereas if the bird were to be 

 turned the other way, the tail would act against the 

 claws, and tend to project the bird from the tree. 

 Thus, though the mechanism of the woodpecker adapts 

 it better for remaining stationary upon the bark of a 

 tree than than that of, perhaps, any other bird ; and 

 though it can run upwards, or round in a direction 

 nearly horizontal, yet it cannot run downwards as 

 well as upwards, and perform those evolutions that are 

 displayed by the creepers and titmice. But there is a 

 power of remaining longer at one point, and that is 

 what the woodpecker requires. 



The other birds that have been hinted at, find their 



