Abstract
Lymphocystis virus has been classified with the icosahedral cytoplasmic deoxyriboviruses (ICDVs) but a detailed structure of the virion has not yet been established. Virus from tumours of European plaice and flounders was allowed to decay and this revealed details of its structure. Freshly prepared virus has a hexagonal outline which breaks down to reveal surface subunits 4.5 nm in diam. and a spheroidal core with tubular material 13 nm in diam. inside it. This tubular material appears to have a periodicity suggesting a helical conformation and may be a deoxyribonucleoprotein. No triangular or pentagonal facets, as found with some other ICDVs, were seen. A possible construction of the virus is proposed.