WARNING COLOURS 209 



they were present ; and it may, therefore, have per- 

 sisted from a time when the butterflies possessed these 

 appendages. 



Similar features in Reptiles 



A similar interpretation applies to the tails of 

 lizards, which break off the instant an attempt is 

 made to capture the animal by seizing this part. The 

 tail is, of course, the first part which the pursuer has 

 the chance of seizing. The great length of the tail, 

 and the rapidity with which it is renewed after being 

 shed, also support this interpretation. 



Similar features in Mammals 



It is very possible that the well-known peculiarity 

 of the tail of the dormouse is to be explained in the 

 same manner. The large bushy tail of the squirrel 

 may possess a similar meaning (among others) , for an 

 enemy in pursuit would be liable to get only a mouthful 

 of fur. In the north of Europe the squirrels which 

 frequent the birches are black, while those on the 

 pines are brown : both varieties, which are probably 

 protective, become greyish in winter, and thus har- 

 monise with the frosted bark. But the tails of both 

 retain their summer colour, and would be thus more 

 conspicuous. This fact was pointed out to me by my 

 fi'iend Mr. H. Balfour.^ 



* On the other hand a seasonal change in the colour of the tail 



