348 
Entozoa of Fishes 
Sub-family VI. Zoogoninae Odhner 1902. 
Genus i. Zoogonoides Odhner 1902. 
Species 1 . Zoogonoides viviparus (Olsson 1808). 
Next to Podocotyle atomon this was the commonest species found at 
Millport. It occurred in Pleuronectes limanda (67 °/ 0 ), PL microcephalus 
(100 °/ 0 ), PI. platessa((j 7 %), and Callionymus lyra (80%). It is thus 
extremely frequent in each of these hosts. In a previous paper (1909 b, 
p. 16) I remarked that the species occurred in Pleuronectes flesus at 
Millport, but that was in error for PI. limanda. The former fish was 
not examined at Millport. The number of British hosts of the species 
is therefore only eight. Six of these are flat fish so that the species is 
a typical Pleuronectid parasite, notwithstanding the fact that Cal¬ 
lionymus lyra is probably the most frequent individual host. 
It almost invariably occurs in large numbers, 100 or more, even in 
young fish. As a x’ule it is most numerous in the rectum but frequently 
it extends throughout the intestine. 
It is described in detail by Odhner (1902), Miss Lebour (1908) and 
myself (1907). 
Sub-family VII. (Derogeninae). 
Genus i. Derogenes Liihe 1900. 
Species 1 . Derogenes various (O. F. Muller). 
This occurred in the oesophagus and stomach of seven hosts, namely, 
Cottus scorpius (60 %)> Gadus callarias (17 %), Gadus merlangus (100 %), 
Gadus minutus (50 %), Gadus pollachius (71 %), Gadus virens (14 %) 
and Pleuronectes platessa (17 %)• Of these the last four are new 
British hosts. The total number of the latter is now 19, but this does 
not by any means exhaust the list, as I shall have occasion to show later. 
The species is the most widely distributed of all marine Trematodes. 
The infection in each host, however, rarely exceeds half a dozen. 
Numerous descriptions of the sjrecies exist. The most recent are 
those by Odhner (1902), Johustone (1907) and Miss Lebour (1908). 
