Abstract
Mytilicola intestinalis reported from oysters on s.-w. and s.-e. coasts of Britain, with level of infection up to 9.5% and 1-4 parasites per oyster. It is also reported from Paphia decussata. Concluded that Mytilicola does not readily infect oysters in presence of mussels and is unlikely to become epidemic in oysters except as result of adaptation or change in environmental conditions. Attention drawn to undesirability of relaying infected oysters in neighborhood of uninfected mussel beds.