W. Nicoll 
243 
the intestinal bifurcation. The somewhat elongated cirrus pouch 
contains only the pars prostatica and the ductus ejaculatorius. The 
vesicula seminalis lies entirely outside the pouch, with which it is 
connected by a fairly long duct, which is bent up alongside the pouch. 
The pouch is divided into two parts by a distinct constriction about its 
anterior third. The posterior part is entirely filled with the pars 
prostatica. The vesicula seminalis, which lies alongside the cirrus 
pouch and somewhat behind it, is a little smaller than the posterior 
portion of the pouch. 
The ovary lies to the right of the middle line immediately behind 
the ventral sucker. It is a small globular body of 0’09 mm. diameter. 
The yolk glands lie on either side of it and a little in advance. Both 
overlap the intestinal diverticula. Each consists of a compact ovoid 
mass of follicles, which is somewhat larger than the ovary but smaller 
than the testes (O'lo x 0'08 mm.). The yolk ducts pass behind the ovary 
and a fairly conspicuous yolk reservoir is formed. There is a large shell 
gland and a small receptaculum seminis but Laurei’’s canal is apparently 
absent. It is somewhat doubtful if the receptaculum seminis is a 
constant structure. In the living specimen it appeared at times to be 
C][uite distinct but sometimes it seemed to be merely a dilatation of the 
oviduct. In no case did it contain more than a few spermatozoa. In 
the preserved specimens its presence could not be detected. The 
uterus is of no great extent and the largest specimen contained less 
than thirty eggs. Possibly none were completely mature. The eggs 
were scattered around the ovary and along the left side of the ventral 
sucker. They are remarkable in possessing a single long filament 
extending from the anopercular pole. The filaments were directed 
backwards and to some extent intertwined. The eggs are slightly 
curved and measure about O’lO x 0’027 mm. and the filaments about 
0*2 mm. 
The systematic position of this form will be discussed after the next 
species has been described. 
Derogenoid.es ovacutus n. g., n. sp. 
(Fig. 6.) 
This is a form which bears a much greater resemblance to Derogenes 
various than the preceding species does, though it presents one or two 
marked features of difference. Numerous specimens were met with 
on one occasion in the stomach of Trachinus draco. The only other 
specimen of this fish which I have had an opportunity of examining 
was obtained from the North Sea and was not infected with this 
Parasitology v 
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