52 
from Holy Island, off the coast of Northumberland (April). The 
cercaria was tailed, with a tail rather longer than the animal, and 
possessed two conspicuous eye spots. The oral and ventral suckers 
were about the same size ; there was a prepharynx, a pharynx, and 
a very short oesophagus, the intestinal lobes reaching not quite to 
the posterior end of the body. The ventral sucker was almost 
central, and there was a conspicuous pear-shaped excretory vesicle. 
The body was covered. with spines. 
On examining the stomach of a Catfish in February I found a 
quantity of immature Trematodes almost exactly corresponding to 
these cercaria. They were without tails, but otherwise agreed 
in every way with those from Buccinum undatum. Most of them 
still possessed eye spots, but a pair of testes was visible, one each 
side just above the excretory vesicle. Most of them were alive and 
very active. A further stage was found in another Catfish, in which 
vitellaria were well developed, and the genital pore was seen to 
the left of the pharynx, with a cirrus sac and vagina opening into 
it. The cirrus sac was in front of the ventral sucker, but details 
were not made out. The length of the body of the young stage 
was 0-3 mm.— 0-4 mm., breadth 0-14 mm.— 0-18 mm.; oral sucker 
0'07 mm.; ventral sucker the same; prepharynx 0-033 mm. long, 
or longer according to the state of contraction; pharynx 0-052 mm.; 
oesophagus about 0-02 mm. long. The older examples measured 
0-60— 0*80 mm. in length. 
The adults of these Trematodes were found in the upper intestine 
of the Catfish, close to the stomach. The largest measured 0-90 
mm. in length, and exactly corresponded to the larval forms from 
the stomach, but with the addition of large yellow eggs, usually 
four in number. These take up a great deal of room in the body, 
and measure 0-099 mm. by 0-066 mm. The unusually large eggs 
hide most of the other organs in the body, and give the worm a 
most peculiar appearance. The vitellaria reach from the posterior 
end of the body nearly to the level of the pharynx. The body is 
covered with spines, and is quite colourless. 
These Trematodes occurred in three out of twelve Catfish 
examined in November and February. The stomachs contain 
usually a great number of remains of Buccinum undatum, and it 
is most probable that an encysted stage is omitted, and there is 
no intermediate host. The life history is probably the following : — \ 
First host, Buccinum undatum; intermediate host, omitted ; final 
host, Anarrhichas lupus. 
