THE GIANT EARTH-WORM OF GIPPSLAND. iy. 
There is no doubt that the worm passes the ccelomic fluid out by its dorsal pores 
into the burrow, and with the fluid must pass the corpuscles, a constant fresh supply 
of which will hence be needed. . 
6.—Nervous System. ‘This has, in the main, the form usual in earth-worms. It 
consists of a pair of cerebral ganglia, united by commissures to a ventral cord. 
The cord cannot be clearly divided either by its external shape or by its structure 
into well-defined ganglia and commissures, and is of about the same width throughout 
its whole length. 
Where the cerebral ganglia join the commissures on either side, a nerve arises 
which runs forward and sends branches to the body wall in the prostomial region. 
(Plate 3, fig. 16, In.) A little lower down, a curiously flattened mass of nerve fibres 
arises from the postero-internal face of the commissure, and immediately breaking 
up into branches enters the muscular walls of the pharynx. (Fig. 16, ph.,n.) In 
section the branches are seen ramifying amongst the connective tissue and muscle 
fibres of the pharyngeal wall. (Plate 3, fig. 10, nc.) This constitutes the stomato- 
gastric system. Still lower down the commissures arises on either side another nerve 
which runs forward, and breaking up into branches supplies the body wall ventrally 
in the region of the mouth. 
The ventral cord gives off in each segment three pairs of branches. ( Plate 5, fig. 
21, v3. n. n3.) Of these three branches, two are placed somewhat close together mn 
the posterior region of the segment, whilst one is situate slightly in front of the 
median line. Where the nerve cord passes (Fig. 21, sept. 0.) through the septum it 
is supported by a definite mesentery, which arises from either side of it, and is inserted 
into the body wall ventrally. This structure runs for some little distance both 
anteriorly and posteriorly to the septum. 
The histological structure is much the same as that described for other earth- 
worms. The whole nervous system is covered by the coelomic epithelium, which over 
the greater portion of the surface consists of nucleate flattened cells. On the ventral 
nerve cord, however, as the under surface is reached, these merge into cubical cells, 
and such also cover the supporting mesenteries. (Fig. 19, ep.) Within the 
epithelium is a definite development of connective tissue, forming a sheath for the 
whole nervous system. As in Pontodrilus, and certain species of Microcheta and 
Plewrocheta, neither sub-neural nor latero-neural blood-vessel is present. 
With regard to the nervous tissue itself, the cerebral gangha consists of (1) a 
sheath of ganglion cells on the anterior and ventral aspects, and (2) a mass.of fibres 
dorsally and posteriorly, amongst which a strong commissural band, passing from side 
to side, is developed, such as is not met with elsewhere in the system. As previously 
noted, no nerves seem to be given off from the cerebral ganglia directly, though one 
arises on each side where the commissures begin. The commencement of these is 
indicated by the absence of ganglion cells, none of which are found in the commissures 
or, as far as could be ascertained, by means of a long series of consecutive sections, im 
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