NO. 8 THE POLYCHAET — RAW 29 



errant families and perhaps in all the sedentaries it has degenerated. 



Regarding the stomodeum, if, as is above suggested, the much- 

 folded form exhibited by the Eunicimorph is the most primitive type, 

 the different errant polychaets present us with suggestions of the 

 stages of evolution between this relatively nonprotrusible folded type 

 and the extremely protrusible cylindrical type of say the Glyceri- 

 morpha. Such an evolution one might expect to be accompanied by 

 great changes in the visceral nervous system, and probably also in 

 the brain. 



To trace the evolution of any form and the deployment within the 

 class, it will be of great advantage to have a starting point, a basic 

 plan, which is all that the present paper can claim to attempt. Were 

 zoologists to attempt to work out by ontogeny and by comparative 

 anatomy the many courses of evolution within the class, the common 

 starting point would soon be apparent. 



