197 
ON TWO NEW TREMATODE PARASITES FROM 
BRITISH FOOD-FISHES. 
By william NICOLL, M.A., D.Sc., M.D. 
{Lister Institute of Preventive Medicine, London.) 
(With Plate IX.) 
In September, 1908, an opportunity was afforded me of examining 
some of the larger food-fishes brought in to Aberdeen fish market. For 
this I have to thank the courtesy of Professor J. Arthur Thomson, who 
kindly provided the necessary laboratory accommodation, and was 
of great assistance to me in various other directions. I have also to 
thank the Government Grant Committee of the Royal Society for 
defraying the expenses of procuring specimens. 
I was enabled to obtain several species of fish which I had not met 
with during my earlier investigations at St Andrews. Amongst these 
were a few specimens of the horse-mackerel {Trachurus traclmrus) and 
the sea-bream (Spams centrodontus), each of which furnished a new and 
interesting species of parasite. During the short time at my disposal 
only a couple of horse-mackerel and a dozen bream were obtained and 
the number of Trematode parasites they contained was very small. A 
larger number of these fishes have since been collected in various 
localities, chiefly at Plymouth, but they have added only sparingly to 
the number of parasites. The form in the horse-mackerel has indeed 
not been met with again; that from the bream has been found on seven 
other occasions. Both forms present several interesting peculiarities, 
and they are not only new species but are types of new genera. For 
the parasite from the horse-mackerel I propose the name, A ncylocoeliuni 
typicuni, n.g., n.sp., and for that from the bream. Zoonogenus vividus, 
n.g., n.sp. 
