122 A FINAL JOURNEY. 



ance of being formed of a single piece ; but, notwithstanding this 

 apparent solidity, a delicate formative membrane everywhere 

 intervenes between the edges of the plates, and by the gradual 

 deposition of calcareous particles to their margins, adds to the 

 size of each in a regular and uniform manner. It matters 

 nothing, therefore, to the Echinus that it is shut up for ever in a 

 hard, unyielding stony box, for, in virtue of this simple but 

 beautiful contrivance, by the same means that it adds to its 

 bodily substance, it also pushes apart the shelly plates of its 

 crusty environment, and makes for itself the additional room it 

 requires. 



There are several species of the Echinus found around our 

 shores, one of the commonest in many parts being the little 

 Purple Egg Urchin (Echinus miliaris), which thrives very well 

 in captivity, and makes an interesting addition to the Aquarium. 

 At large on the sea-shore, it is generally found in holes and 

 crevices of the rocks, not unfrequently taking up its abode in a 

 deserted hole of that rock-boring mollusc, the pholas ; but in the 

 Aquarium it is very fond of covering itself with bits of gravel, 

 which it holds on by means of its suckers, and, thus adorned, it 

 marches about the bottom of the tank. 



Nothing, in relation to these animals, is more extraordinary 

 than the amount of injury they can sustain without being 

 materially affected thereby. A remarkable instance of this 

 insensibility to mutilation is given by Mr. Patterson, who once 

 cut an Echinus horizontally into two nearly equal parts, for the 

 purpose of examining the intestines and ovaries, which nearly 

 fill the shell. These vital portions of the animal's organization 

 were taken out, and the divided shell was thrown aside ; but, being 

 put into a vessel of sea-water some time afterwards, Mr. Patter- 

 son was not a little surprised to see the two portions of the empty 

 shell put out their suckers and walk about, "apparently as 

 unconcerned as if the loss of intestines and ovaries had been an 

 e very-day occurrence." Let there be no mistake, however. It 

 was a mere piece of bravado on the part of Master Echinus to 

 exert his power of locomotion under such circumstances ; and 

 there can be no doubt, though the fact is not mentioned, that 

 before long the poor fellow got to the end of his journey and 

 walked no more. 



If we do not mistake, some ancient erudite somewhere declares 



