No. i.] THE METAMERISM OF NEPHELIS. 39 



bipolar cells, and these cells resemble the " Leydig's cells " 

 above mentioned and the "colossal" cells of the connectives. 

 These intermuscular nerve rings are joined longitudinally by ten 

 lines of bipolar cells, a single cell in each line joining two con- 

 secutive groups of bipolar cells. The cell body of these cells 

 lies about midway between any two rings. These connective 

 bipolar cells are also strictly comparable to the " Leydig's 

 cells." This system is complete in that a ring may receive 

 stimuli, send forth motor stimuli, and send impulses to other 

 parts of the same system. In its application to the origin of a 

 metamere composed of five annuli it confirms Whitman's 

 proposition that the five-ringed metamere arose from the three- 

 ringed metamere by the doubling of the second and third 

 Clepsine rings. The third annulus in Nephelis is the posterior 

 half of (Clepsine) two, and four in Nephelis is the anterior half 

 of (Clepsine) three. 



TJie Sympathetic System. This is well developed over the 

 wall of the entire alimentary tract. It is connected with the 

 central system at the collar. It passes off from the collar in 

 three pairs of branches, a dorsal, a lateral, and a ventral, which 

 soon fuse and form an intricate meshwork with the fibers from 

 the many multipolar cells on the muscular wall. There is some 

 evidence that the sympathetic system persists in the post-anal 

 region as a remnant of the system that functioned when the 

 anus was terminal. 



NEW YORK UNIVERSITY, 

 February i, 1897. 



