460 



ANNUAL REPORT SMITHSONIAN INSTITUTION, 1962 



D 



Figure 2.-Conventbnal phylogenetlc arrangement of the free-llvmg extant echmoderms 

 L suggested by their larval forms. A, Ophiuroidea, and B, Echmoidea, both groups 

 aS eluteus-type larva. C, Holothuroidea, and D Asteroidea, both groups havjng 

 the aurlcularia-type larva. On the left is the dipleurula larva, from which all the other 

 larvae arise during development. 



