ap.cil 



fr.bod 



~ som. 



C eye 



prot 



prot 



set.sacs 





% ( 



wm'-M QUO 



prvt 



set.sacs 



sens, h 



fr.Jjod 



para, 



FlG. 32". Nereis. Later stages in the development. A, stage at which the pn.tntmch and tl.u 

 apical tuft of cilia first become distinct ; B, somewhat later stage, in which the stomoda al 

 iuvagination is being formed, and the rudiments of the mesoderm bands are distinct ; (', late 

 trochosphere stage in which there are rudiments of the setigerous sacs ; I), somewhat later 

 stage, in which the parapodia have begun to become prominent and the provisional setse 

 project freely ; E, larva with three segments ; an. anus ; ap. cil. apical cilia ; "p. p>. apical 

 plate; eye, eye ; />. bod. frontal bodies; int. intestine; 1. max, longitudinal muscle; mes. 

 mesoderm; mo. mouth ; new. pi. neural plate; para, parapodia; pip. n,-. pigmented area; 

 prot. prototmrh ; m ,m. h. sensory hairs : x,i . sncs, setigerous sacs ; som. second scimatnblast and 

 group of cells formed from it ; st. stomodseum ; tent, tentacles. (After E' B. Wilson.) 



