TWO YOUNG NATURALISTS. 51 



ever, this difference between the two : the Dromia is 

 said to be provided with special claws for planting the 

 creatures on its own back, where they grow and some- 

 times completely cover it, while in the spider-crab the 

 growth may be due to natural causes. The result, 

 however, is the same, and enables stratagem to supply 

 the place of agility, for thus covered they are able 



to remain concealed and motionless until some prey 

 shall venture within reach of their claws. 



In connection with this it will be recollected that 

 during the conquest of Algeria the natives on several 

 occasions made use of a similar stratagem, and that 

 'walking bushes' glided unharmed during the night 

 into the midst of the advanced guard. These children 

 of the desert were no doubt proud of their invention, 

 and had no idea that they were merely imitators of the 

 miserable crabs. There is nothing new under the sun ! 



