W. Nicoll 
339 
are directed backwards and become intertwined into a spiral. Together 
they form a continuous thread on which the ova have the appearance 
of being stuck. The ova are all situated on the inner side of the 
spiral and at equal distances apart. In the vagina they tend to 
become separated from the spiral and are probably deposited singly 
although I have observed a complete spiral extruded. The filaments 
are not motile. 
The ova number about fifty. They are dark brown in colour, with 
a moderately thick shell and have a characteristic shape. From the 
lateral aspect, which is the view usually obtained, they appear comma- 
shaped with the broad end pointing forward and the narrow end 
tapering off into the filament. One surface is therefore convex, the 
other concave, and the former is that which lies along the spiral. 
When turned over on to one or other of these surfaces the outline 
appears ovoid, the broad end again being anterior. In size they vary 
considerably. The length is 0'063—0084 mm.; the transverse breadth 
0’032—0'037 mm. and the breadth from convex to concave surfaces 
0027—0'33 mm. at its maximum. The average of these, to which the 
majority approximated, is 0'073 x 0'033 x 0 - 030 mm. No segmentation 
takes place before the deposition of the eggs. 
It is obvious that the foregoing description does not agree with 
that of Odhner (1901 and 1902) but that it agrees very closely with 
Stossich’s description of Distomum labri (1887) and Distomum gobii( 1883). 
The chief differences contained in Odhner’s description are (1) the testes 
are entire and oblique; (2) the yolk-glands overlap the intestinal 
diverticula posteriorly, and form a continuous narrow band across the post- 
testicular space ; (3) the genital aperture is just over the intestinal bifur¬ 
cation and the cirrus-pouch extends to the middle of the ventral sucker ; 
(4) the shape of the ovary is somewhat different and it is not directly 
in front of the testes. These differences, if constant, would be sufficient 
to constitute a difference in species. The probability, however, that 
they are not without the limits of variation induced me to examine 
carefully every individual specimen, amounting to nearly 200, in my 
collection. These were mostly obtained on the South coast of England 
and from such varied hosts as Trigla pint, Gobius paganellus, Blennius 
pholis and gattorugine, Lepidogaster gouanii, Labrus mixtus, Ctenolabrus 
rupestris , Zeugopterus punctatus and Anguilla vulgaris but a remarkable 
degree of uniformity was observed, and that they all belonged to one 
species there can be no question. In not one single case were the 
testes otherwise than strictly tandem ; in almost every instance they 
