102 
EGHINOSTOMUM SECUNDUM, NICOLL. 
Fikst Host. 
Second Host. 
Final Host. 
Littorina littorea. 
Mytilus edulis. 
Gardium edule. 
Oyster Catcher 
(Hacmatopus ostra- 
legus.) 
Mactra stultorum. 
Herring Gull (Larus 
arqcntatus.) 
Mija arenaria. 
Macoma balthica. 
Another trematode from the Budle Mussels occurs in the liver 
(see Plate I., fig. II.) It is not so plentiful as those in the foot but 
is often to be found encysted beween the lobes of the liver. By 
carefully pressing it out of the cyst it is seen to be elongated, length 
(>46 mm., and its body is covered with short spines. Not much 
structure can be made out, the granular excretory system being 
most noticeable when the worm is still in the cyst, but these quickly 
disappear. There is an anterior oral and a posterior median sucker, 
the former leading to a scarcely perceptible pharynx. Two clear 
canals are faintly visible down each side which communicate to- 
gether anteriorly ; this is perhaps the excretory system devoid of its 
granules. The worm appears to be a species of Distomum, and 
this stage apparently has not been described. 
The cockle, Cardium edule, of Budle besides the encysted trema- 
tode in the foot, contains three more species. One of these is the 
sporocyst and cercaria stage of the ' pearl trematode ' which is the 
cause of the pearls in the mussel. Another sporocyst in the liver 
was described by me in last year's report, and also later by Mr. 
Nicoll (op. tit.). This has evidently nothing to do with those in the 
foot. A third species of sporocyst occurred in one cockle in March 
(see Plate II., fig. III.); some hundreds were present in the liver. 
They were very contractile and of various shapes, had no eyes, aud 
were not ciliated. Each contained four or five round bodies which 
were probably far advanced germ balls. 
In one specimen out of 190 of Littorina littorea from Budle 
examined the kidney was full of the cercaria) of a second species. It 
occurred in great abundance in long sporocysts about 1 mm. long 
(see Plate II., fig. IV.) This appears to be the Cercaria linearis of 
Lespes (op. cit.) which he found in the kidney of Littorina littorea. 
