ON SOME QUEENSLAND THEMATODES. 
373 
its anterior end two main exci-etory vessels open. These 
cross over the posterior intestinal loop and run forwards as 
far as the sides of the pharynx, where they end blindly. In 
their forward course they lie close to, and fairly parallel to 
the intestinal limbs, re-crossing them near their anterior end. 
On their outer sides they give off a number of mostly un- 
divided branches; on their inner aspect they give off a 
number of branches which, anastomosing freely, form a 
network in the middle of the body (figs. G and 33) lying 
ventral to the uterus. From all the branches finer tubes are 
given off which end in flame-cells. These finer tubes are 
apparently intra-cellular, as not more than one nucleus could 
be made out in the wall of any of those examined. The walls 
of the larger vessels — the main trunks, network and branches — 
as well as the vesicle are composed of a nucleated syncytium. 
Nervous System. — Two large cerebral ganglia, com- 
posed of the usual nerve-cells and fibres, lie, one on either 
side, in front of the pharynx (fig. 29). They are joined by a 
thick commissure, and give off a number of fine nerves to the 
integument in the fi’ont of the body. Behind, each gives off 
a thick nerve, the lateral nerve-cord, containing in its course 
many nerve-cells as well as fibres (fig. 7). These nerve-cords 
run backwards just outside the intestinal limbs, and in the 
extreme posterior end of the body, behind the excretory 
vesicle, join together to complete the circuit. Branches are 
given off, both on the outer and inner aspects of these nerve- 
cords, and at the points where they leave the main trunks 
little heaps of nerve-cells usually occur. The internal branches 
fuse with one another so as to form a network on the ventral 
surface of the body, just internal to the muscular layers, and 
ventral to the network of excretory vessels (fig. 27). 
Genital System. — The common genital pore is situated 
on the ventral surface just beneath the oesophagus — i. e. in 
front of the intestinal foi*k. The testes are large branched 
bodies lying near the posterior end, but completely within the 
space bounded by the intestinal loop. They are somewhat 
obliquely placed one behind the other. The posterior, lying- 
