1. An Athesmia sp. from two species of jackals (Canis adustus Sundervall, 1846, and Canis mesomelas Schreber, 1775) in northern Tanzania is described.

2. While considerable variation in size and internal morphology was observed, these differences do not appear to be significant.

3. There being no constant morphological features to establish a new species, these specimens are for the present considered to be A.foxi Goldberger and Crane, 1911.

4. The difficulties in the identification of Athesmia are discussed and the present position in the genus briefly reviewed.

5. Histopathological studies were carried out with negative results and reference is made to other reports of such studies in the literature.

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.

It is apparent that under the conditions of the observations recorded in this study the host-parasite relationships of the two species of snails and their respective strains of S. haematobium exhibit marked similarity in certain respects but differ in others. Higher cercarial infection rates were obtained in B. globosus than in B. truncalus at relatively low miracidial exposure levels but the daily mean cercarial outputs of each species at the same miracidial exposure level were similar. A higher frequency of production of large numbers of cercariae was recorded for infividual B. globosus than for B. truncatus. The mean cercarial prepatent periods for B. globosus and B. truncatus at a level of 7 miracidia were each 32 days, but infected B. globosus lived appreciably longer than infected B. truncatus. The hourly output of both species exposed to stimuli for the same period of time was broadly similar. Peaks of cercarial production were generally reached earlier by individual B. truncatus (2 weeks) after onset of shedding than by individual B. globosus (4–5 weeks), although erratic shedding was observed for both species.

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.