THE METAMERISM OF NEPHELIS. 



A CONTRIBUTIOA' TO THE MORPHOLOGY OF THE NER- 

 VOUS SYSTEM, WITH A DESCRIPTION OF 

 NEPHELIS LATERALIS. 



CHARLES L. BRISTOL. 



TABLE OF CONTENTS. 



Introduction 1 7 



Historical 18 



Methods 18 



Systematic 21 



Description 24 



General of N. lateralis 26 



Somites 27 



Head Region 28 



Anal Region 28 



Summary 28 



Habitat 29 



Habits, Food, etc 30 



Nervous System 32 



Whitman's Description of the 

 Nervous System of Clepsine 33 

 Nervous System of Nephelis .... 36 



Central Nervous System 37 



A Typical Neuromere 38 



Leydig's Cell 39 



Median Nerve Cells 41 



The Fibrous Portion 41 



Innervation of a Body Meta- 



mere 43 



Innervation of the Terminal 



Somites 44 



The Anal Region 44 



The Head Region 46 



The Intermuscular Nerve 



Ring 51 



The "Large" Nerve Cells 57 



The Sympathetic System 58 



Summary 61 



Bibliography 63 



Description of Plates 64 



Abisreviations 72 



Introduction. 



The work which forms the basis of the present paper was 

 begun in 1891 at Clark University, Worcester, and continued 

 at the Marine Biological Laboratory at Woods Holl and Chicago 

 University, and I wish to acknowledge here my indebtedness to 

 the authorities of these institutions for the facilities and the 

 Fellowship privileges granted to me. To Professor Whitman, 

 at whose suggestion I began the investigation, I am deeply 

 indebted for aid and encouragement and for many courtesies 

 extended to me. I am under obligations to Dr. Wm. M. Wheeler 



