354 
Entozoa of Fishes 
towards each side of the body, with the left testis somewhat in advance 
of the right. They however may approach each other and even overlap, 
the left still being in advance. The right one, on the other hand, may 
be in advance, and from this overlapping position they may diverge till 
they come to lie obliquely tandem with the right in advance. In this 
position they are never widely separated and generally lie towards the 
right side of the body. The position of the ovary varies correspondingly. 
When the testes are in the first position described, it is usually situated 
immediately behind the pharynx, in the middle line. As the testes 
change in position it tends to move obliquely forwards to take up a 
limiting position at the right side of the pharynx. 
It is impossible then to describe in a word the topography of the 
genital glands, but if that be attempted it were best summed up in: 
Ovary towards the right side, just behind the level of the pharynx; 
testes, oblique, a short distance behind the pharynx. 
The testes are usually almost globular and have a diameter of 0'28 mm. 
The cirrus-pouch is short and stout and its extremity lies about a third 
of the body length from the posterior end. It usually lies towards the 
left side. Its internal structure is similar to that in P. aculeatus. 
The diameter of the ovary is 0'25 mm. and it is thus little less than 
the testes. Just behind it lies a large shell-gland, with a Laurer’s 
canal but no receptaculum seminis. The yolk-glands form a continuous 
arc across the body behind the rhynchus. The follicles are more 
irregular in size and disposition than those of P. aculeatus, and they 
are more massed together. The lateral follicles extend back to about 
the level of the blind end of the intestine, there being usually a slight 
inequality on the two sides so that those of the left reach a trifle further 
back than those on the right. The yolk-ducts are very long and pass 
down one on each side to unite behind the ovary. 
The uterus is as a rule not so voluminous as in P. aculeatus and it 
is only in specimens over 3 mm. that it attains any great length. In 
smaller specimens it is confined very much to the left side and consists 
merely of an ascending limb from the ovary to the middle of the yolk- 
glands and thence a descending limb to the genital sinus. It increases 
in size by sending a loop down on the right side of the cirrus-pouch, 
but mainly by forming several convolutions in front of the pharynx, 
between it and the yolk-glands. The ova are very numerous and light 
yellow to dark brown in colour. They measure 0 - 026—0'030 mm. by 
0016—0'02I mm. the average being 0 029 x 0 019 mm. They are 
therefore of much the same size as those of Prosorhynchus aculeatus. 
