336 



A r 



A^. M. Stevens and A. M. Boring. 



B C D B 



N 



A. — Whole worm showing planes of section. B — D. — Head-pieces after 2 weeks' regeneration. 

 E. — Head-piece after 4 weeks' regeneration. F.— Middle-piece after 2 weeks, showing ventral union 

 of anterior edges (e — f), V of new tissue (g — e — h), and posterior regeneration. G. — Middle-piece after 

 2 weeks, showing anterior regeneration where the edges have not united as in F. H. — Middle-piece 

 after 19 days, showing heteromorphic tail. L. — Middle-piece after 4 weeks, showing more advanced 

 anterior regeneration of the type shown in F. M.- — Middle-piece after 4 weeks, showing anterior 

 regeneration of the type shown in G. N. — Posterior regeneration of middle-pieces, showing super- 

 numerary appendages. O — P. — Regeneration in tail-pieces, 2 weeks. R — S. — Lateral regeneration, 

 4 weeks. T — X. — Young worms, still in jelly, with appendages just developing. 



