ECH1NODERMA TA 22$ 



which has had the temerity to attack the holothurian. 

 A large lobster has been seen thus ensnared, and quite 

 unable to move. It might be supposed that this mode 

 of defense would be fatal to the sea cucumber, but 

 that animal merely goes into retirement for a time, and 

 regenerates the lost parts. 



The wormlike species (Synapta) behave differently. 

 The posterior part of the body is amputated, while the 

 head with its feelers buries itself in the sand or mud. 

 The Echinodermata, whatever their origin, have them- 

 selves given rise to no other groups. They represent a 

 separate branch of the tree of life, as do the sponges and 

 mollusks. 



