116 



SUBKINGDOM VEETBBEATA. 



the former replaced by the brown-olive of the latter, the two 



birds could hardly be 



Mg. 188. 



SiaRa si3lis. Blue-bird. 



distinguished.* 



Motacillidse. — The 

 Wagtail incessantly 

 flirts its tail up and 

 down, accompanying 

 each elevation with a 

 jerking spread. This is 

 due to the length of the 

 tarsi (Fig. 184), which, 

 on the lowering of the 



bill, throws the centre of gravity in front of the feet and 

 gives the body a constant tendency to tumble forward. The 

 quickly-expanding tail striking against the air, raises the 

 head again with little effort. 



Fig. 189. 



Fig. 190. 



MotaciUa alba, White Wagtail, 



PhUamUa lusdnia. Nightingale. 



Sylvicolidffi (wood-warblers). — The Xiglitmgale of 

 Europe has been famed from time immemorial for the sweet- 

 ness of its voice. It is ii shy bird, but its song is occasion- 

 ally heard during the day, though it is most pleasing in the 



* Their social nature corresponds as fully as their physical, and the blue-bird 

 would fleure as appropriately in the beautifiil legend of " The Babes in the Wood " as 

 the traditional robin-redbreast. 



