532 



PASSEEINES. 



This wonderful power, however, is only developed at the 

 sacrifice of another locomotive faculty, for they are bad w^alkers. 

 With their short limbs, activity on their feet is impossible ; and 

 if by chance they are placed on the ground, with difficulty they 



Fit. 240.— \V iiidow hwallowa {Huundo rusticti, Linn.). 



'1®^ 



rise again on the wing. On the other hand, their sight is 

 excellent — equal to even that of the Eagle or Falcon. According 

 to Spallanzani, who made numerous experiments on the Swallows, 



