CONTENTS 



Introduction page 225 



Systematic Account 227 



Cephalodiscus hodgsoni 228 



Ccphalodiscus nigrescens 233 



Cephalodiscus detmis 235 



Cephalodiscus fumosus, n.sp 238 



Cephalodiscus kempi, n.sp 241 



Internal Anatomy 245 



Orientation 245 



Proboscis 246 



Collar cavities 247 



Organs of the trunk 248 



Muscular System 250 



Vascular System 251 



Nervous System 252 



Classification of the Species of Cephalodiscus with a List of known 



Forms 254 



New Data Summarized 259 



List of Literature 259 



Plates XXXIII-XXXVIII following page 260 



