AMPHINEURA 



Two orders are described in this class : Placofiora and Aplaco- 

 flora. One family of the first order is known, the Chitonids, 

 and two in the second, the Chetodermids and the Neomenids. 

 Numerous colonies of chitons are found on all the tide- 

 washed stretches of the calcareous rocks of madreporic 

 origin or on the volcanic rocks of some islands. Chitons are 

 covered with a calcareous-chitinous dorsal armour of six to 

 eight articulated plates, allowing the animal, if detached from 

 the rock which it clings to with its fan-shaped foot, to roll up 

 into a defensive ball like the mammal, the armadillo or some 

 isopod crustaceans, like the wood-louse, etc. 



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