No. I.] 



THE METAMERISM OF NEPHELIS. 



51 



nucleus has the same size and characteristics of the typical 

 "median nerve cell." Still further dorsally, lying between 

 the capsules ascribed to metamere I, I find the pair of remain- 

 ing "median nerve cells" here compressed into a spindle 



ANT. CAPSULES. 



COLLAR 



Tkxt-fig. 2. — The ' ' median " cell in neuromere I as seen in a horizontal section through the 

 dorsal part of the collar. The section passes through the capsules, i.i.i., of Fig. 13, PI. VI. 

 Camera outlines. ^ immersion oc. 3. Reduied one-half. 



form (Fig. 2 in the text). This discovery enables us now to 

 say, without reserve, that every element recognized in the body 

 neuromere is found in the supra-oesophageal ganglia, and, 

 therefore, that the supra-oesophageal ganglion or "brain" is 

 homologous with a body neuromere. 



The Intermuscular Nerve Ring. 



Intimately connected with the central nervous system and 

 probably closely related to it in origin is a remarkable periph- 

 eral system of nerves hitherto, so far as I have been able to 

 learn, wholly unknown and unsuspected by all investigators 

 who have worked especially on the details of the nervous sys- 

 tem of leeches. For the discovery, I must again thank the 

 gold-chloride method of staining, for the only elements of it 



