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No. 6.— The Nervous System of Nereis virens Sars. À Study 
in Comparative Neurology. By J. I. HAMAKER.! 
CONTENTS. 
Page Page 
Introduotlotie ui: sil Wiles ed e. Peripheral Fibres . . . 105 
Methode can. Dart cle Donnin 0.106 
Part dl. Destripon,.« «u... De Ws. MODAN. cp ar an UO 
I, @opograpny. vos. 0. . UL ee a POOO Liste « + . « LOY 
a. Brain 02) 3. Brain. >. ¿A a8 
. “Mushroom Bodies” . . . 109 
- Optic-Gangllod: w una A 
. Ventral Nerve Cord. . . . 112 
b. Sub-esophageal Ganglion 93 
c. Typical Body Segment . 94 
d. Parapodial System. . . 95 
DIS 0 » 
2. Protective Tissue . . , . 96 ‘-DONITOSOMES A AUS 
Oy USA A we ee VC fF NGEVO PIDU WoW yo se ke 
4. Ciliated Groove . . . . . 100 ti Giant Pibres: 277 “HS 
5. Ventral Nerve Cord. . . . 100 D. Fibres of Set À v ao ein ‘M6 
6. Nerve Fibres . x , , . . 102 O: Fibres:of Set-B w O 
Se Gant Fibres ows LOR d. Fibres of Set C . . . . 118 
Dv, BDIGH OL SOLAS su 22 LUO MSUMMANS ut una in sue. LAS 
C Eibresotset so’, . , 108 Bibliography . +. . 5... 0... 200 
d. Fibres of Set C . . . . 105! Explanation of Plates . . . . . 124 
INTRODUCTION. 
ALTHOUGH 80 much has been written on the nervous system of repre- 
sentatives of all the chief groups of the metazoa, we are as yet far from 
thoroughly understanding the action of the myo-neural mechanism of 
any animal. It is true, much light has been thrown upon the subject 
during the last decade through the use of the newer methods of investi- 
gation; but the many valuable facts that have been established are as 
yet so disconnected, that they can scarcely be said to be more than stig- 
gestive. In no case has the myo-neural system of an animal been at all 
completely worked out. In the higher animals the complexity of this 
system makes such a task almost impossible. At any rate, the most 
1 Contributions from the Zoölogical Laboratory of the Museum of Comparative 
Zoölogy at Harvard College, under the direction of E. L. Mark, No. XCI. 
VOL. XXXII. — NO, 6, 1 
