294 MOVEMENTS OF THE ECHINUS. 



My own experience incontestibly proves that the 

 suckers in question are used for precisely the same 

 purpose as those situated in any other part of the 

 body. I am enabled to state, from having repeatedly 

 witnessed the phenomenon, that ike Echinus can 

 walk about with equal facility while lying on its 

 back as in its more natural position. The advan- 

 tage of this power to the animal under certain cir- 

 cumstances will be apparent upon a little reflection. 



With regard to the spines, I fancy their purpose 

 is almost solely to assist the Urchin to burrow in the 

 sand, and to protect it from the attacks of its enemies. 

 It may be, however, that at particular times they 

 serve as aids to locomotion, but that their assistance 

 can be, and is, often dispensed with entirely by the 

 animal, I can most positively assert. 



My experiments were always conducted in glass 

 vases, up the smooth, polished sides of which my 

 specimens frequently advanced. Upon reaching the 

 surface of the water, I have seen an Urchin roll 

 completely round and move along on its back, then 

 after a time change its position, and travel round 

 the circumference of the vessel while attached by its 

 side, the body of the animal being sometimes in- 

 verted. 



At such times as these it must be quite evident 

 that the spines would be totally useless, and that by 

 the suckers alone did the animal perform its interest- 

 ing movements. 



