MONILIGASTER GRANDIS, A. G. RB. 341 
interganglionic regions as are the nerve cords of a leech. The 
ganglia, however, spread along the cords so that the inter- 
ganglionic regions become very short, and two or three other 
post-oral ganglia fuse with the subceesophageal ganglion itself. 
The ganglion lies in the anterior region of a segment. 
A nerve arises on each side from the anterior edge of the 
cerebral ganglion, the branches of which clearly supply the 
prostomium. 
Five nerves arise on each side from the inner surface of the 
commissure, and pass on to the pharyngeal wall to form a 
stomato-gastric system. I find no nerve ring on the pharyn- 
geal wall. Ordinarily three nerves arise on each side from 
each ganglion. One of these arises from the anterior portion 
of the ganglion, and this passes at once into the septum (see 
this branch, of the right hand side, in Segment vii in fig. 27. 
The septa are supposed to have been dissected entirely away 
in Segments 1x and x). In the case of the thickened septa 
this nerve can be very clearly seen running in between the 
muscular layers of the septum; it passes into the body-wall, 
and runs round towards the dorsal region, behind the inter- 
segmental groove. 
The other two nerves arise very near together from the 
middle region of the ganglion. They run outwards near the 
inner surface of the body-wall until they reach the inner seta 
row. Here they penetrate the body-wall, and run round 
towards the dorsal region between the muscle and the epi- 
dermis. The more posterior one of the two gives off a large 
branch soon after penetrating the body-wall, which also runs 
round towards the dorsal region. 
These three nerves may be called the first, second, and third 
nerves of the segment respectively. 
The first nerve gives off a small branch, which bifurcates 
and is supplied to the septum. 
The second and third nerves each give off a small branch 
before arriving at the inner seta line; these branches join and 
supply, I believe, the viscera of the segment (except the 
alimentary canal), 
