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A Trematode Larva from Buccinum undatum and 
Notes on Trematodes from Post-Larval Fish. 
By Marie V. Lebour, D.Sc. 
Naturalist at the Plymouth Laboratory. 
With Figures 1 to 7 at the end. 
On May 30th, 1916, a number of large Buccinum undatum were brought 
in from the trawling grounds ; 40 of these were examined and 34 were 
found to contain larval Trematodes. Another lot in the spring of 1917 
contained about the same percentage of infected Mollusks. Two species 
of Trematodes were present, both contained in the digestive gland, which 
was absolutely riddled with them. 
The first, which was in 4 out of 40 Buccinum, was identified as Cercaria 
neptunt Lebour (1912), previously found in both Neptunea antiqua and 
Buccinum undatum from the Northumberland coast. This is a thick- 
tailed cercaria contained in long colourless redize which are tightly 
packed in the digestive gland and give to this organ a characteristic 
sickly grey appearance quite unlike its ordinary healthy state, so that 
infected specimens can easily be recognized by cutting a small aperture 
in the spire of the shell and examining the portion of digestive gland 
exposed. The further life history of this cercaria is unknown. 
The second species occurs much more commonly and was found in 
30 out of 40 Buccinum examined. The colour of the infected digestive 
gland is this time an unhealthy pinkish yellow, which is characteristic. 
The cercariz are contained in sporocysts which occupy almost the whole 
of the spire of the shell. 
The anatomy of this cercaria shows it to be almost certainly a larval 
stage of Zoogonus viviparus (Olsson), the life history of which is so far 
unknown (Odhner, 1902). This Trematode in the adult state lives in the 
intestine of many common fish. It has been recorded from 11 different 
species, 9 of which are from the Channel—Zeus faber, Blennius gattorugqine, 
Blennius ocellaris, Solea vulgaris, Solea variegata, Pleuronectes limanda, 
Pleuronectes microcephalus, Pleuronectes platessa and Callionymus lyra. 
Nicoll (1914) regards Callionymus lyra, Pleuronectes spp. and Solea spp. 
as undoubtedly their chief hosts, all of these bemg common on the 
trawling grounds where the Buccinum were caught. 
