1. Laboratory studies showed two types of cages to be suitable for exposing uninfected B. glabrata in field habitats as a means of locating S. mansoni miracidial infestations.

2. Tests conducted in tanks under simulated field conditions showed that miracidia moved away from the point of inoculation in non-random fashion and congregated at the margins of the tanks.

3. In a natural habitat, miracidia located and infected caged snails at distances of 33 cm vertically and 106·7 cm horizontally.

4. The pattern of infection was similar in the simulated field and field experiments, but field infection rates were lower.

5. For transmission studies in field habitats, caged laboratorybred snails should be placed at the margin of the habitat to ensure the maximum snail-miracidium interaction.

1. The four physico-chemical characteristics of water tested— volume, salinity, pH, and turbidity—were each found to affect infection of B. glabrata by S. mansoni miracidia.

2. The rate of infection decreased as the water volume increased from 90·6% at 0·005 litre to 47·5% at 50 litres.

3. The rate of infection decreased as sodium chloride concentration increased, from 78·7% at 0·5 ppm to 2·1% at 4200 ppm. Above 4200 ppm no infection occurred. The activity of the miracidia was affected above 1200 ppm. The snails became non-motile at above 4800 ppm and died within 10 hours at higher concentrations.

1. Laboratory and field trials were carried out to investigate the influence of depth on the infection of B. glabrata by St. Lucian S. mansoni miracidia.

2. In both laboratory and field experiments, miracidia located and infected snails to a depth of 122 cm.

3. The degree of infection seems to be related to the size of a habitat and its water volume.

4. Infection rates were high at the miracidial point of entry where miracidium-snail interaction was maximum and at the water surface where miracidia eventually congregated.

Both brown trout, Salmo trutta, and rainbow trout, S. gairdneri, from Hanningfield Reservoir, Essex, and adjacent rearing channels, harboured Eubothrium crassum throughout 1968. There was no seasonal cycle of occurrence or maturation of the cestode.

2+ brown trout introduced into the reservoir in the spring acquired heavy infestations during their first summer in the reservoir. Most of these cestodes are apparently lost from fish which have been in the reservoir for a year or more. Possible reasons for this loss are discussed.

Afromacroderoides lazerae gen. et. sp. nov. (Allocreadiidae; Walliniinae) is described and figured from specimens collected from the intestine of the African freshwater fish Clarias lazera from the White Nile near Khartoum, Sudan. The new genus is distinguished by the shape of its cirrus sac, the presence of a bipartite seminal vesicle and a spiny cirrus. It is differentiated from the related genera Paramacroderoides and Pseudoparamacroderoides.

138 wild duck of five species: Anas plalyrhynchos plalyrhynchos, A. penelope, A. crecca, A. acuta and Spatula clypeata taken in East Anglia, England were examined for trematodes, cestodes, nematodes and acanthocephala. Prevalence data are tabulated and maximum intensities recorded. The waterfowl were taken in the autumn and early winter and were presumed to be migrants coming in from western Europe.

The route of migration and development of Ancylostoma ceylanicum, when given orally, has been described for the first time in hamsters. A predominant feature of the migration is the absence of any lung journey. This is unlike A. caninum, A. duodenale and A, brazilicnse when larvae are similarly given to an abnormal host. The larvae of A. ceylanicum apparently had no submucosal migration

Four new species of digenetic trematodes of birds from Palawan Island, Philippines, are described: Galactosomum palawanense (Heterophyidae) from Ceyx r. rufidorsus; Euamphimeruspalawanensis (Opisthorchiidae) from Gallus g. gallus; Strigea palawanensis (Strigeidae) from Strix seluputo wiepkeni; Paramonostomum palawanense (Notocotylidae) from Centropus sinensis bubttlus. Stephanoprora sp. (Echinostomatidae) from Spilornis cheela palawanensis and Euamphimerus sp. from Chalcophaps i. indica are briefly described but not allocated to species as the specimens are incomplete.

East African Fasciola gigantica apparently does not reach sexual maturity in mice, rats, hamsters, guinea pigs and rabbits. The order of recovery of flukes from the highest to the least was as follows : hamsters, guinea pigs, mice and rabbits. Rats were completely refractory to infection. The more highly susceptible animals also had a higher recovery rate of flukes. Mortality in animals appeared to be related to infection.

We have investigated, the accuracy of a nematode egg flotation technique, using magnesium sulphate and the Clayton-Lane centrifuge system routinely used in diagnostic laboratories, to estimate the numbers of H. rubidus in porcine faeces. Eggs present in 3 g samples taken at random from a night's faecal collection from one pig were shown to be randomly distributed. The technique was not of reproducible accuracy and various sources of error were investigated.

Recent collections of helminths from the clariid catfish, Clarias batrachus (L.) in India and Malaysia have included Bovienia serialis (Bovien), a species originally described by Bovien (1926) from a single whole specimen and fragments of others. The generic diagnosis formulated many years later by Yamaguti (1959) and based indirectly on one of these fragments has inevitably led to some confusion regarding the characters of the genus. With the collection of new material it is now possible to emend the generic diagnosis and redescribe the species.

1. The protein nitrogen, carbohydrate and amino acid contents of the rat duodenum, jejunum, upper and lower ileum have been determined for up to 3 hr following the feeding of a glucose-containing test diet.

2. The changes in distribution of Hymenolepis diminuta within the intestine and the changes in worm total nitrogen and carbohydrate have been followed over the same period following the same diet.

3. The glucose and TCA-soluble carbohydrate contents of the uninfected gut were approximately double those of the parasitized animals.