BY S. J. JOHNSTON. 281 



of these passes off from the postero-lateral corner, and may be 

 traced outwards across half the length of the posterior border of 

 the worm, and close to it(Fig.l). The second passes off from 

 the middle of the same limb of the vesicle, and runs parallel and 

 just posterior to the terminal part of the intestinal limb; while 

 the anterior branch, which is much shorter than the others, 

 comes ofi' near the anterior end of the vesicle. From all three 

 lateral branches, numerous capillary vessels are given off, those 

 from the posterior lateral branch especially forming a close net- 

 work of vessels that extends over the whole of the posterior 

 region of the body, lying just beneath the cuticle. 



Nervous System. — A pair of cerebral ganglia, consisting of a 

 considerable number of nerve-cells, lie one on either side of the 

 oesophagus, a little behind the pharynx. They are connected by 

 a thick band of nerve-fibres passing dorsal to the oesophagus, 

 but no ventral commissural fibres are to be found. From each 

 cerebral ganglion (Fig. 1), a thick nerve-trunk passes outwards 

 and backwards in an oblique direction to the posterior border of 

 the body, passing on the mesial side of the ovary, on the one 

 hand, and of the cirrus-sac, on the other. Each of these nerve- 

 trunks, in the region just in front of the point where it passes 

 the anterior loop of the intestinal limb, gives off a large branch, 

 only a little smaller than the main trunk, which runs outwards 

 parallel and close to the anterior loop of the intestine and in front 

 of it. From the cerebral ganglia also arise four or five fine nerve- 

 fibres on each side, which run forwards and are distributed to 

 the anterior sucker and pharynx, and the region in front of the 

 sucker. Numerous nerve-fibres pass off to various parts of the 

 body from the main lateral trunks, and from the two main 

 branches into which each main trunk divides. The nervous 

 system cannot be made out in whole specimens, but has been 

 drawn in on Fig.l from a series of horizontal sections. 



Genitalia. — The genital aperture, which lies in a depression in 

 the middle of the left lateral border, leads into a comparatively 

 spacious common genital chamber. The gonads are of large size, 

 and lie in the other side of the body, that is, on the right of the 

 middle line. They lie in the space formed by the U-shaped 



