PTEROBRANCHIA 



PTEROBRANCHIA 



Rhabdopleurida 

 Cephalodiscidea 



ORD-REC 

 CRE-REC 

 ORD-REC 



^^^ Includes: Palaeo-echinoidea, Paleo-echinoidea, Palechinoidea, Euechinoidea. 



^"^^ Includes: Melonechinoida, Melonitoida, Stirodonta, Aulodonta, Camaro- 

 donta, Endobranchiata, Ectobranchiata. 



"° Includes: Gnathostomata, Atelostomata. 



'^^^ Includes: Pedata. Subclasses sometimes accepted: Actinopoda, Apoda, Me- 

 galopoda. 



