35 
posterior sucker may be entire and circular in outline, or 
divided into pairs of separate suckers. One genus has a 
small secondary or “ adhesive ” dise attached to the large 
one. These parasites live for some time after the death 
of the fish and adhere very closely to the gills or skin, in 
fact it is sometimes quite impossible to detach them with- 
out injury. <A very convenient way to remove them is 
to leave the gills, or portions of the skin to which they are 
attached, in fresh water for some hours; this treatment 
eventually kills the parasite and at the same time causes 
it to relax its hold. 
I._Species with posterior sucker entire :- 
Callicotyle kroyeri, Diesing. 
From the cloaca of Rata clavata. It is also found 
on other rays, but always in the cloaca. The posterior 
sucker has seven strong bands radiating from an inner 
circle, the spaces between the rays are conical in outline 
with the apices towards the centre. 
Phyllonella solew, van Beneden and Hesse. 
‘ 
Attached to the seales on the ‘‘ white side” of the 
common sole. This trematode is of moderate size but 
easily overlooked owing to the colour resembling that of 
the fish. 
? Placunella pint, van Beneden and Hesse. 
This trematode which we identify as P. pzni has only 
been found on the gills of the yellow gurnard, T'rigla 
hirundo. Wt has eight distinct and two indistinct rays in 
the posterior sucker. 
Deplectanum cequans, Diesing. 
Found on the gills of the “bass.” A very small 
species and sometimes abundant. 
II.—Species with no distinct posterior sucker, having 
