A medium containing inorganic salts, vitamins and amino-acids is described for the in vitro cultivation of the amphistome, Orthocoelium scoliocoelium, from the rumen of buffalo. Based on the properties of rumen fluid, this medium promoted and sustained normal egg production, at 37°C temperature and pH 7·4 to 7·8 for 15 days. In contrast to other media used, no patho-physiological alterations except abnormal cytoplasmic lipid, were detected. Since the parasites produced normal eggs, it is concluded that this medium is suitable for short-term cultivation of the parasites.

Anisakis sp. larvae when incubated in vitro produced secretions/excretions which released the dye from an azocoll substrate, indicating protease activity. The optimal conditions for enzyme release and activity were a temperature of 37°C and a pH of 7·5. In addition the larvae showed peak behavioural activity at 37°C, the body temperature of the final, marine mammalian host. The results are discussed in relation to their possible significance to the invasion of the various hosts in the life-cycle.

The nematode family Trichostrongylidae is divided into six subfamilies Trichostrongylinae, Libyostrongylinae, Haemonchinae, Cooperiinae, Ostertagiinae and Graphidiinae which are briefly reviewed. The key is based mainly on specimens examined by the authors and includes one genus in the Trichostrongylinae, three genera in the Libyostrongylinae, six in the Haemonchinae, seven in the Cooperiinae, 17 in the Ostertagiinae and two in the Graphidiinae. Pseudostertagia, Pararhabdonema, Parostertagia, Obeliscoides and Travassosius are briefly described, figured and considered as genera of uncertain affinities. Nine genera, namely, Moguranema, Neocooperia, Bergheia, Mazamastrongylus, Paramecistocirrus, Ostertagiana, Ostertamia, Graphidiella and Trichostrongyella, specimens of which have not been available to the authors for examination, are listed giving details of host, habitat and geographical location, together with a summary of the diagnostic characters as described by the original authors.

An adult female Dipetalonema setariosum (Mönnig 1926) recovered from the pleural cavity of Meriones libycus and bearing an adherent cell mass was examined by means of electron microscopy. The host reaction consisted exclusively of macrophages and was associated with disruption of the cuticular membrane and invasion of the cuticle itself. There was no evidence of prior activity by other cell types. Initiation of damage appeared to be associated with the release of lysosomal enzymes by the macrophages. Within the reaction a localized breaching of the cuticle had occurred and cells had penetrated the internal tissues of the worm. It is suggested that macrophages may play a role in the elimination of effete worms from an established population.

Of 10,362 cattle examined in Bangladesh, 4,368 (42·15%) harboured hydatid cysts. One to three-year-old cattle had the lowest (11·34%) and those over nine years old the highest (93·21%) infections. Organ involvement was as follows: liver 35·18%, lungs 32·02%, spleen 0·80%, heart 0·41%, kidney 0·25%, omentum 0·11% and both liver and lungs 31·20%. Fertile cysts occurred in 8·11%, sterile in 74·91%, calcified in 9·43%, suppurative in 6·04% and undeveloped in 1·51% of animals.

The protein composition of various developmental stages of Dipetalonema viteae was analysed on polyacrylamide slab gels in the presence of sodium-dodecylsulphate. When the total proteins of adult male and female parasites, microfilariae, eggs, and third-stage larvae were compared, apparent qualitative similarities between mature and immature filariae were observed. However, several stage specific components were also identified.

A single oral dose of 50 mg/kg of oxamniquine administered to mice with mature infections of Schistosoma mansoni gave rise to a hepatic shift and almost total elimination of the male worms. Regression of the reproductive system and a conspicuous reduction in size took place in the residual females which eventually resembled sexually immature adults. A second dose of oxamniquine had no apparent effect on these females within a period of 28 days following this treatment and it is suggested that this change in reproductive status is the result of discontinued male stimulation.

Dactylogyrus legionensis n. sp., a monogenean parasite from the gills of Barbus barbus bocagei from the Esla river (León, NW Spain), is described and its population dynamics discussed. It differs from the closely related species, D. balistae, in the presence of vaginal armour and in the morphology of the copulatory organ. D. legionensis was found on 30·40% of barbel, with a mean intensity of 13·71 and maximum infection levels in autumn-winter. The prevalence and intensity of infection rose significantly with the age and length of the barbel, and were higher in females than in males. D. legionensis showed preference for the second and first gill arches, sector III and the internal zone of each hemibranch.

Ascaridoid nematodes occurring in South American mammals are divided into categories based on their possible origin. The affinities are discussed of five species so far known only from the Neotropical Region. Toxocara alienata (Rudolphi, 1819) is reported from Nasua rufa socialis, Procyon cancrivorus, and Tayassus torquatus. The specimens from T. torquatus are described and found most closely to resemble Toxocara mackerrasae from south-east Asian and Australian rodents. Anisakis insignis from Inia geoffrensis is transferred back to Peritrachelius Diesing, 1851, on account of the structure of the lips and spicules. P. insignis is shown to exhibit remarkable convergence of lip structure with Lagochilascaris turgida from Didelphis marsupialis.

Galeiceps longispiculum (Freitas & Lent, 1941) from Pteronura brasiliensis is confirmed as a species distinct from G. cucullus (Linstow, 1899) and G. spinicollis (Baylis, 1923), but G. simiae (Mosgovoy, 1951) is considered to be a synonym of G. spinicollis. An error in the host record of G. spinicollis is corrected from Cercopithecus leucampyx kandti to Lutra maculicollis kivuana. Ascaris dasypodina Baylis, 1922 from armadillos, including Cabassous unicinctus and Tolypeutes matacos, is redescribed and placed in a new genus Bairdascaris. The question is raised as to whether some species in Lagochilascaris, Galeiceps, and Toxocara may have crossed directly by sea from Africa to South America, rather than entering via North America.