W. Nicoll 
121 
diameter measures 0'55 to 0'77 mm. and the average dimensions of 
the sucker as far as could be determined are 0'60 x 0 - 68 mm. The 
ratio of the mean diameters of the suckers is therefore approximately 
7 : 8. The suckers are thus more nearly equal than in P. biliosum. 
The ventral sucker is situated at a distance of 1*2 to 2T mm (i.e. five- 
elevenths of the body length) from the anterior end, so that it is only a 
short distance in front of the middle of the body. 
The pharynx is a small globular body situated entirely dorsal to 
the oral sucker and measuring 0‘15 mm. in diameter. It is succeeded 
by a short oesophagus about 0'21 mm. long. At the bifurcation the 
intestinal diverticula diverge widely, passing round the outer side of 
the testes, thence finding their way between the yolk glands and the 
uterus in a sinuous course. They extend to within 0 - 2 mm. of the 
posterior end of the body. They are thus decidedly longer than in 
P. biliosum. Their walls, however, are not so much crenated. The 
excretory vesicle resembles that in P. biliosum. 
The genital aperture is situated exactly at the intestinal bifurcation. 
The cirrus-pouch is small and slender, being only 0'35 mm. long and not 
reaching the level of the testes. It contains a slightly convoluted 
vesicula seminalis and a short prostate and ductus. 
A remarkable feature of this species is the presence of a large well- 
defined mass of subcuticular gland-cells around the genital aperture. 
This mass extends from the level of the pharynx to the level of the 
vesicula seminalis and its breadth is about half the width of the body. 
The cells are closely packed together and in some places are three and 
four layers deep. Each cell has a fairly distinct duct leading to the 
ciiticle. It is surprising that this structure is not present in P. biliosum. 
In the latter the usual scattered cervical glands are present in consider¬ 
able numbers, but there is no tendency for them to be aggregated 
together. 
The testes are situated immediately in front of the ventral sucker 
which they touch but do not overlap. They also touch the intestinal 
diverticula without overlapping. They measure 0‘5 x 0'3 mm., their 
longer diameter being decidedly transverse, instead of oblique as in 
P. biliosum. They are very thick, occupying almost the whole thickness 
of the body, and they are overlapped by the uterus only to a slight 
extent. Their outline is roughly triangular and the margins are irregu¬ 
larly crenated. 
The ovary lies immediately behind the ventral sucker a little to 
the left of the middle line. It is a transversely oval body, measuring 
Parasitology vii 
9 
