TABLE OF CONTENTS. 



Page. 



Preface 1 



History of the work, with an account of the material studied 1 



General method of treatment 4 



Synonymy 8 



Systematic treatment 8 



Embryolo^, development and anatomy 10 



Variants and aberrants 12 



Philosophical conclusions 12 



Relative status of the recent crinoids 15 



Illustrations 18 



Identification of the specimens upon which this work is based 19 



Individuals and institutions to which the author is indebted 20 



History of the subject 21 



General history 21 



History of the intensive work upon the comatulids 56 



General survey of the history 58 



Glossary of terms used in the description of a comatuUd 59 



Explanation of symbols 107 



Description of a comatulid 108 



Identification of recent comatulids 114 



Structure and anatomy 118 



History of the subject 118 



General history 118 



General survey of the history 124 



Organization of the crinoids 125 



General remarks 125 



Eggs and segmentation 132 



Development of the larvee 132 



Echinodermal skeleton 132 



Autotomy 140 



Orientation and the metameric divisions of the echinoderms 142 



Relationships between the digestive tube and asymmetry 152 



Zones of similar skeletal potency 161 



Internal skeleton 164 



Skeleton of the heteroradiate echinoderms 164 



Effect of external mechanics upon the crinoids 174 



Earliest crinoids 183 



Blastoids 186 



Nervous system 189 



Eye 190 



Sensory setae 190 



Excretory organs 190 



Genital ducts 190 



V 



