142 TOKIO KABURAKI 
placed very closely together and rest on the surrounding tissue. 
The cells, each with an oval nucleus in its basal portion, contain 
a great number of coarse, highly refractive granules in the finely 
sranular protoplasm. In some cases the cells were observed to 
be vacuolated in the distal portion of the cell. So far as I have 
observed, any special glandular cells are altogether absent in 
the epithelium. 
Nervous System.—the brain is a bilobed organ, situated 
at the anterior end of the body between the ventral wall and the 
anterior termination of the intestinal canal. From the brain- 
mass arise numerous nerves which are distributed over the 
various parts of the anterior end of the body. But their 
arrangements were not clearly made out. Each half of the 
organ is formed of a very finely granular ground-substance, in 
which small nerve cells occur much more abundantly towards 
the periphery than in the central part. At various points the 
mass is perforated by fine muscular fibres in the dorso-ventral 
direction. 
Kach half of the brain-mass is continuous posteriorly with 
one of the longitudinal nerve cords, which proceed straight 
backwards, until finally they joi together at the posterior end 
of the body. The cords themselves are very thick and usually 
present, in cross-section, the characteristic spongy or finely 
reticulate appearance. Small nerve cells are scattered in sparse 
numbers in the substance of the cords. Throughout their 
entire course the longitudinal nerve cords are connected by 
very numerous transverse commissures. Laterally they give 
off numerous branches towards the nerve plexus, which lies 
beneath the outer longitudinal muscles of the body and extends 
completely round the body. ‘The plexus consists of a close 
network of fine fibres. 
Eyes (PI. 4, fig. 6).—The only special sense-organs which 
I have seen in the present species are the eyes. Each consists, 
as usual, of a pigment cup and of numerous visual rods. The 
pigment cup is of a bell-like shape with its opening directed 
outwards and upwards, and is as usual formed of very minute, 
closely packed, spherical granules, of a dark-brown colour. 
