THE RADIATE INDIVIDUAL 111 



doubtful, for in the evolution of the earthworm, as in that 

 of the fish, it would appear that the new digestive opening 

 provided was a mouth and not an anus, and that the 

 formation of an anus at what would have otherwise been the 

 dome end of a medusoid series would be incompatible with 

 active locomotion of marked degree. This is, however, 

 anticipating later chapters. What might be presumed is 

 that a near ancestor of the echinoderm had certain powers 

 of locomotion, and that these have been lost ; more or less 

 stationary habits and the evolution of tube-feet being later 

 developments (Fig. 40). 



