The Trematode Parasites ofTurritella communisLmk. from Plymouth and Naples

In 1931 Dr M. V. Lebour drew my attention to a larval Trematode (one of the “Hugetailed Monostome” group of H. M. Miller, 1925) which occurred quite frequently inTurritella communisfrom the Rame Mud, Plymouth. During 1932–4 I examined 541Turritella communisfrom the same locality and an 8 per cent. general infection with four species of closely related cercariae was recorded, but the species which was common the previous year did not occur once. 180Turritella communisfrom Naples revealed a 5 per cent, infection of two other closely related species.