290 WILLIAM BLAXLAND BENHAM. 
exactly at the opposite end to the pore (Pl. XVI, fig. 25). In 
somite x11 the vesicle is shorter and wider, whilst the pore is 
placed nearly half way between its blind end and the rosette of 
tubules (fig. 26). It seems probable that the whole set of 
loops in Microcheeta is really one continuous tubule, opening 
into the vesicle at one extremity, and leading to the funnel at 
the other: the whole tubule being bent into a number of 
U-shaped loops, each of which is twisted round itself. The 
whole nephridium, though so complicated, may be compared 
to that of Lumbricus, by considering the smaller lumen of 
the latter, bent upon the larger and more glandular portion, 
and then wrapped and twisted ; whilst the very small muscular 
region of Lumbricus is enlarged into the exceedingly well- 
marked vesicle of Microcheta. 
The Nervous System.—Thecerebral ganglia (Pl. XVI 
bis, figs. 34, 35, c. g.), or supra-pharyngeal ganglia, lie embedded 
in the muscular wall of the pharynx, or rather in the radiating 
muscles of this organ; they lie very close together, but are not 
fused into a single mass as insome Harthworms. A commissure 
(n. com.) passes down on each side of the pharynx, at the junc- 
tion of the buccal region with the pharynx, and the two com- 
Missures unite on the ventral surface in the fourth annulus, to 
form the subpharyngeal ganglion. 
The following ganglia lie towards the posterior part of each 
somite, and, as in Lumbricus, are not very distinct (Pl. XVI 
bis, fig. 36). 
In each somite nerves come off both from the ganglionic en- 
largements and from the ventral cord itself; three pairs, usually 
from the former, and one pair from the latter. 
The ganglion-cells are, as in Lumbricus, more or less nume- 
rous throughout the cord, not being confined to the ganglionic 
swellings. The three “ giant-fibres”’ are here present, as also 
a sheath, but with no muscles in the sheath; neither subneural 
nor latero-neural vessels are present (figs. 37, 38). 
In transverse sections of the nerve-cord, the ganglion-cells 
(n. g. c.) are seen to lie apparently, each in a little capsule, as it 
were, of connective tissue (ct.), which dips into, and amongst 
