F. D. Weidman 
271 
The oesophagus passes from the centre of the posterior portion of 
the oral cavity, is very short, simple, and surrounded by a heavy muscular 
coat, a continuation of the muscle of the oral sucker, together with 
large and numerous so-called salivary cells. In addition, a notable 
sphincter is present at the oesophago-oral junction; this muscle has 
been commonly missed by other writers. The oesophageal muscle 
continues over the bifurcation to include both arms of the caeca, accom¬ 
panied laterally by cuticle and subcuticular cells, but no “salivary” 
ones. Here again there has been no agreement among writers. Otto 
is very positive about an oesophageal muscle being present while Duff 
and Fischoeder are silent about it. The caeca are broad, not branched, 
lightly sinuous and pass at once to the lateral borders which they follow 
posteriorly, each caecum ending blindly behind the acetabulum close 
to cuticle. The caeca contain black granular material and vegetable 
cells, they are notably constricted in places, forming sacculations above 
and below, one so large as to closely approach the size of the oral sucker. 
Upon reaching the acetabulum the caeca pierce the vitellaria which 
lie close to the cuticle, shortly emerging close to the cuticle with 
vitelline follicles still present mesially but not laterally. 
The Reproductive System. 
The male organs. The testes are preequatorial, preacetabular, 
lie ventral to and between the caeca and antero-posteriorly to each 
other, the anterior but slightly to the right and but slightly ventral to 
the posterior. The posterior border of the hind testis lies slightly 
posterior to the equator, reaches almost to the acetabulum and one 
or two of its branches extend slightly below the level of the anterior 
acetabular border. The anterior border of the anterior testis extends 
well forward beyond the ventral border of the oral sucker. Each 
consists of an irregular, small body from which six to eight long, wavy, 
coarse, tube-like branches extend. They are mostly bifid and extend 
in all directions; a few occur ventrally, whilst by far the greatest number 
extend dorsally between the caeca. The branches thus come to overlap 
the neighbouring testis, while their fields 1 overlap and almost coincide. 
On account of their branching character their whole mass is difficult 
to estimate, but it is about equal to that of the oral sucker and certainly 
much less than that of the acetabulum. Spermatozoa were numerous in 
the body and branches of the testes in both worms that were sectioned. 
1 Nomenclature advocated by Stiles. 
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