286' 



THE UNIVERSE. 



They cannot be cut with kon, but a violent shock shivers 

 them." Plutarch believed that they were composed only 



Ifin. Sea-hedgehogs or Urchins.^ 1, Erhuius Delalandi. 2, Echinus perforans. 



of fish-bones interlaced. But it appears that the philo- 



1 The sea-urchin lives a solitaiy and almost serlentary life, hid in tlie sand or 

 among the sea-weeds, or stuck on to some rock. Some authors allege that by aid 

 of its prickles it hollows out for itself a hole in the rock. The real fact is, that 

 these animals are often found lodged in cavities so regular and so well propor- 

 tioned to their shape as to give rise to the supposition that if they have not 

 entirely formed the hollows, they have at least enlarged and rounded them. In 

 this there is nothing improbable when the stone is of a soft and argillaceous 

 nature; but frequently these urchins are found lodged in granite, and it is diffi- 

 cult to comprehend how the animal could hollow out so hard a material. — Mangin, 

 Les MysUres de VOcean. 



