European chub Leuciscus cephalus collected from five localities in the lowland and subalpine regions of Austria were analysed for oestrogenic effects of endocrine-disrupting chemicals and the presence of the plerocercoid of the tapeworm Ligula intestinalis. Of 1494 chub analysed, only seven (six males, one female) were found to be infected with single, but large plerocercoids up to 15 cm in length. Ligula-infected fish showed comparatively immature gonads, as demonstrated by the gonadosomatic index and gamete developmental stages. Plasma levels of the egg precursor protein vitellogenin also showed concentrations ranging below the detection limit. The present results indicate that chub infected with L. intestinalis and exposed to exogenous oestrogenic compounds can result in reduced gonadal maturation and produce false oestrogen-positive diagnoses in male fish. For plasma vitellogenin levels, L. intestinalis infections can result in false oestrogen-negative diagnoses in male and female fish.

Interactions between extracts of adults or cercariae of the pathogenic blood fluke Sanguinicola inermis and lymphocytes of carp Cyprinus carpio were investigated in vitro by monitoring proliferation of pronephric and splenic lymphocytes at 10 and 20°C. Adult S. inermis were more mitogenic than cercariae at both temperatures. Splenic lymphocytes only responded to adult worm extracts at 1O0C, whilst pronephric lymphocytes responded in a dose-dependent way to all extracts except those of cercariae at 10°C. Higher concentrations of the extracts reduced the degree of lymphocyte stimulation. These effects on pronephric and splenic lymphocytes of carp may be associated with stimulation and/or suppression of the immune response of the host. K E Y WORDS:Cyprinus carpio . Sanguinicola inermis Lymphocyte . Mitogen

1. Maritrema apodemicum sp. nov. from the long tailed field mouse, Apodemus sylvaticus sylvalicus (L.) on Skomer Island is described and compared with other species of the genus.2. 14·6% of the mice were infested, the % infestation being greater in the males, 20·3%, than the females, 5·4%.3. A brief discussion of the genus and of other species occurring in mammals is included.