No. 2.] A NEW MARINE TRICLAD. 179 
tudinal trunks correspond exactly to the points of exit for the 
lateral nerves. At the posterior end of the body, where the 
longitudinal nerves unite, a small plexus of somewhat variable 
character connects their fused ends with the marginal nerve. 
This I take to be the typical arrangement of the main nerve- 
trunks. Ina few cases, however, I observed a marked deviation 
from this schema; some of the transverse nerves in the retro- 
pharyngeal region had broken up into a rude plexus, much like 
the plexus which occurs in fresh-water Triclads throughout the 
whole area between the longitudinal cords. 
The marginal nerve has a clearly defined outline along its 
inner border, but along the outer edge it is quite irregular, and 
breaks up into an indistinct plexus of smaller fibres not easily 
resolved in Syucelidium. In specimens of 2. candida, which 
had been hardened in a much flattened condition, I found no 
difficulty in tracing this plexus for some distance externally 
to the marginal nerve as a pretty net-work of fibres with 
rather uniform meshes. I have no means of telling how 
extensive this plexus may be. A long series of experiments 
with methylene blue, undertaken for the purpose of establish- 
ing this point, failed completely. I am, however, inclined to 
believe with Woodworth, that the plexus, of which the marginal 
nerve is only a condensation, extends through the longitudinal 
muscles, especially in Syxcelidiwm, where this system is so 
powerfully developed. 
In young specimens, a ring-nerve may be seen in the walls 
of the oesophagus (Fig. 3, p#r) connected with two lateral 
pharyngeal nerves (f#/). The innervation of the pharynx 
thus resembles that of Guzda as described by Lang (812, '81°). 
I have been unable to make out a connection between the 
lateral pharyngeal nerves and the longitudinal trunks, but I 
doubt not that such a connection exists. 
On the histology of the nervous system I have little to add 
to the accounts of other writers (Iijima, Lang, and Chichkoff). 
In L. candida, where the histological elements are more robust, 
I have found spindle-shaped ganglion cells in the marginal 
nerve similar to the ganglion cells which occur in the longi- 
tudinal nerves of the same and other Triclads. These cells 
