228 THE BOOK OF A NATURALIST 



velvety-black back became visible, and made in 

 its setting of red and yellow leaves a prettily 

 coloured picture. Presently he disappeared, then 

 quickly rose again with more earth ; but the 

 leaves evidently annoyed him, and to rid himself 

 of them he suddenly began agitating his body in 

 an astonishing way, for while the movement lasted 

 he looked like a black ball spinning round so rapidly 

 as to give it the misty appearance of a revolving 

 wheel or the wings of a hovering hawk-moth. 

 This swift motion on his part set the leaves flying, 

 and mole and dust and dancing leaves together 

 formed a little whirlwind or maelstrom. When 

 it was over the leaves settled again on the mound, 

 and twice again the extraordinary performance was 

 repeated, and the little animal being then almost 

 above the ground I foolishly put out my hand to 

 pick him up, and before I could properly grasp him 

 he was gone. 



The spinning or revolving motion was an illusion 

 of the sight produced by the exceedingly rapid 

 motions of the skin while the animal was stationary, 

 and the deluding motions were effected by means 

 of what the anatomists call the " twitching muscle," 

 which is possessed in some degree by most, if not 

 by all, mammalians. We see it every day in our 

 domestic animals, especially in the dog when he 

 shakes himself after a swim ; and if he has shaggy 

 hair and it is full of water he throws it off so 

 violently that it fills the air with a dense spray 

 for several feet around him. He could not do this 



