MIMICRY 55 



these have a special interest for us, because they illus- 

 trate the way in which the zeal of the seeker after adap- 

 tive contrivances may run away with him if not kept 

 well in hand. For there is scarcely any limit to the num- 

 ber of problematical cases which have been described 

 as adaptive resemblances, and so explained as having 

 arisen through natural selection, whilst the evidence 

 in favour of such a supposition is in many cases highly 

 questionable. On the other hand, in a number of 

 well-marked instances, the theory of mimicry certainly 

 seems to afford an adequate explanation of the way 

 in which many curious characters and structures may 

 possibly have come into existence. 



The families of the Mantidts and Phasmidcz, includ- 

 ing the walking-stick and leaf insects, afford many 

 examples of animals which both in their colour and 

 configuration show a very close resemblance to sur- 

 rounding inanimate objects. This resemblance must 

 have the effect of concealing them from their enemies, 

 and more particularly from their prey, as* indeed, a 

 study of their habits indicates quite clearly. 



Phyllopteryx, an Australian fish allied to the well- 

 known sea-horse (Hippocampus), is provided with a 

 number of irregular appendages of ragged skin 

 resembling the seaweed amongst which this animal 

 is found. In this way the characteristic symmetrical 

 appearance of a live animal is got rid of, and the 

 creature is rendered extremely difficult of observation. 

 Here, again, the concealment afforded is probably 

 useful in leading to the deception of the smaller 

 organisms upon which the creature feeds. 



