CLADORCHIS WATSONI (CONYNGHAM) 
As we pass into the posterior half of the bulb the diamond-shaped lumen becomes 
a slightly oval slit whose angles shortly afterwards are turned down, thus forming a 
crescentic-like space in cross section. At the hinder end of the bulb these turned 
down corners are cut off from the central lumen and form two lateral diverticula, the 
pharyngeal pouches (Fig. 7, PI. IV). The diverticula, although they have their origin in 
the turned down corners of the lumen, soon come to lie dorso-lateral of the central 
channel, and this alteration in relative position is caused by the central channel passing 
toward the ventral surface of the body. The pharyngeal pouches consist of the same 
kind of loose vacuolated tissue as the bulb, they are very thick-walled and with 
small lumina. 
Behind the bulb the lumen of what may now be called the oesophagus deepens, 
and in the region of the anterior border ot the genital pore, the central portion of the 
alimentary canal is no longer surrounded by the characteristic tissue ot the bulb, 
though the two dorso-lateral diverticula, which still persist, are. The lumina of 
these diverticula then become slightly coiled so as to appear twice in one section, and 
then each of them fades out and disappears altogether. At about the level where the 
anterior third ot the body joins the posterior two-thirds, the oesophagus divides into 
the two lateral diverticula, and around the ^-shaped lumen at this point is a thick 
bulb or sheath of muscle fibres mostly circular in their arrangement, though some are 
radial. Around them is a layer of longitudinal muscles (Figs. 5 and 6, PJ. IV). The lateral 
diverticula now pass outwards and begin to include between them the reproductive 
organs. Each diverticulum is flattened sideways and has a considerable dorso-ventral 
axis. They give off no secondary diverticula, though they are wavy or wrinkled, 
especially posteriorly, and here also they diminish in size, pass dorsally, and come to 
an end just about the level of the anterior lip of the great posterior sucker. 
It does not seem possible to make out any cells lining any part of the gut. No 
epithelium is recognizable. The lumen is lined by a deeply-stained layer which looks 
like mucus, very thin in the pharynx but quite thick in the intestinal diverticula. At 
the outer surface of this deeply-staining layer, darkly-stained structures, which may be 
nuclei, are here and there to be seen. The whole rests on a very definite basement 
membrane, and outside this in the region of the diverticula is a single layer of longi- 
tudinal muscles, the whole recalling in appearance the structureless lamella and the 
muscle-tails of the ectoderm cells lying on it, in a Hydra (Fig. 10, PI. IV). 
The Excretory System. — The excretory pore lies in the middle line above the 
posterior sucker. It opens into a tube lined with cuticle directly continuous with 
that which clothes the body. This canal is pushed a little way out of the median 
line and lies, in the single specimen reduced to sections, a little to the left. Its walls 
soon thicken, and numerous darkly-stained structures appear in its periphery, there 
may be nuclei or possibly sections through minute muscle fibres. Passing forward 
the canal enlarges and forms a spacious vesicle which still lies over the sucker, 
