XIV] CLASSIFICATION 369 



Order 4. Molpadiidae. 



Buccal tentacles small, tube-shaped, unbranched or slightly 

 branched, no other tube-feet ; gill-trees and radial canals 

 present. 



Ex. Molpadia. 



Order 5. Elasipoda. 



Buccal tentacles with shield-shaped ends, body flattened, 

 no gill-trees present. 

 Ex. Elpidia. 



Order 6. Pelagothuriidae. 



Buccal tentacles with shield-shaped ends, and long ampullae 

 projecting into swimming collar; no gill-trees and no other 

 tube-feet. 



Ex. Pelagothuria. 



s. & M. - 24 



