iv • CONTENTS 



NO. 4 NOVEMBER 



G. H. Parker and E. G. Titus. The structure of Metridium (Actinoloba) 

 marginatum Milne-Edwards with special reference to its neuro-muscu- 



lar mechanism. Seven figures (one plate) 433 



G. H. Parker. The effector systems of actinians 461 



E. I. Werber. Experimental studies on the origin of monsters. I. An eti- 

 ology and an analysis of the morphogenesis of monsters. Eighty-nine 

 figures 485 



