The presence of five nematodes previously unknown in the British pig population is reported i.e. Globocephalus urosubulatus, Oesophagostomum quadrispinulatum and three species of Trichostrongylus. T. vitrinus is recorded for the first time from Sus scrofa domestica. The gastro-intestinal strongylates were encountered most frequently in older animals and were especially numerous in the spring and early summer, whilst the incidence of Ascaris suum and Trichuris suis declined with the increasing age of the host.

Over a period of seven years several series of observations were made on infestations of Ostertagia ostertagi and Cooperia oncophora on the herbage of pastures grazed by calves. A regular seasonal pattern was revealed. The concentration of larvae on the herbage falls to a low level in spring. Susceptible calves turned out at this time may begin to contaminate the pasture in mid-May but it is not until July that the infestation on the herbage increases significantly. Generally the increase is to a high level which is maintained with little change until the following spring.

Evidence is presented which indicates that contamination of the pasture in the first half of the grazing season is far more effective in the production of an infestation on the herbage than is contamination in the second half of the season.

In a discussion of the epidemiology of parasitic gastro-enteritis the formerly accepted view, that clinical helminthiasis results from a continuous build-up of infection in the calves and on the pasture is rejected. It appears that the parasites complete little more than one generation each year.

The results of these observations suggest a simple and widely applicable means of controlling parasitic gastro-enteritis in calves.

Annulospira oculata gen. et sp. nov., belonging to the family Thelaziidae is reported from the orbital cavity of a parrot. It has coarsely annulated cuticle, well developed buccal capsule, narrow caudal alae, pedunculated cloacal papillae and a gubernaculum.

Le Roux (1930) erected the genus Ashworthius for nematodes, from Tragelaphus scriptus sylvaticus—the bushbuck, which closely resembled Haemonchus but which had a symmetrically placed dorsal lobe of the bursa and apparently lacked a gubernaculum. The four species of Ashworthius, so far discovered, are described as lacking a gubernaculum, but numerous specimens from Syncerus caffer caffer received by the author, and identified as A. lerouxi Diaouré, have a distinct gubernaculum. Paratype specimens of A. lerouxi and specimens of most of the other species were examined to determine if the gubernaculum is in fact absent. As a result of this study the genus is reviewed to correct errors in some of the published descriptions and to provide new information where possible.

Redescriptions of the cercaria, metacercaria and adults of N. triserialis and N. imbricatus are given. Cercariae developed in Lymnaea peregra and Bithynia tentaculata respectively and infected snails were collected from the Wentloog level, near Cardiff, South Wales. The characters adopted by Dubois for distinguishing species of this genus are more reliable than any alternative and the number of ventral glands is considered to be a reliable diagnostic feature in spite of suggestions to the contrary. The possibility of using chemical differences between the metacercarial cysts and other stages as a means of speciation is discussed.

The Indian gerbil, Tatera indica indica, was collected in the arid western Rajasthan at Bikaner during the first weeks of July, August and September 1968. From sixty gerbils a large number of nematodes belonging to the genera Streptopharagus Blanc, 1912, Rictularia Froelich, 1802 and Trichuris Roederer, 1761, together with a few cestodes, were recovered from the stomach and intestine. The Streptopharagus sp. described below, vastly outnumbered the other worms and appears to be a new species.

Four new genera (each containing one new species) belonging to the order Rhabditida have been described from Jodhpur Sewer. Mesodiplogasteroides n.g. (subfamily Diplogasterinae) is distinguished from the closely allied genus Butlerius by the absence of setose papillae on the head and the presence of a rudimentary bursa in male. Operculorhabditis n.g. (subfamily Rhabditinae) is characterized by the presence of a flap-like, deciduous, cuticular operculum covering the vulva which is well posterior. Praeputirhabditis n.g. (subfamily Rhabditinae) is unique in possessing prepuce-like loose cuticle through which the tail can be protruded. Saprorhabditis n.g. (sub-family Protorhabditinae) has neither a glottoid apparatus nor a median oesophageal bulb but possesses an oesophageal collar. The genus Matthesonema is transferred to the subfamily Rhabditinae. Rhabditis (Rhabditella) octopleura is being recorded for the first time from India.

This redescription is based on specimens taken from the leg of a moorhen, Gallinula chloropus (L.), that was found alive, but paralysed, in Adwick-le-Street, Doncaster, Yorkshire. The heel joints of both legs were distended and found to be infected with nematodes. The paralysis may have been caused by debility due to blood loss as a result of injury, rather than a direct effect of the parasite because a post-mortem examination also revealed “severe bruising of the right ribs and the liver had ruptured to produce an internal haemorrhage.”

The development of the parasitic stages of O. ostertagi is described and illustrated by a series of figures.

Some confusion exists as to the correct identity of Ostertagia trifurcata. The relevant literature is reviewed, and it is concluded that the observations of Sarwar (1954, 1956) pertaining to the identity of O. trifurcata are correct; that is that the genital cone possessed papillae. Teladorsagia davtiani is therefore a synonym of O. trifurcata and O. pinnata a valid species.

Aporocotyle argentinensis n.sp. from the bulbus arteriosus of Merluccius hubbsi is described and figured and compared with the other four known species of the genus. Of 240 hake caught at 12 localities off the coast of Argentina, 54 were infected with a total of 83 flukes, 33 fish with one fluke each, 15 with 2 flukes each, 4 with 3 flukes each, and 2 with 4 flukes each. The incidence of infection at individual localities varied from 0% to 45%. The phylogeny of Aporocotyle in hake is discussed; of the three species occurring in hake, A. spinosicanalis appears to be the most highly evolved.

Experimental infections with strongyles were carried out using ponies reared worm-free. Infection with Strongylus vulgaris was produced by artificially administering larvae to housed ponies. Infection with small strongyles was produced both by this method and also by exposing hitherto worm free ponies to heavily infested pasture. The shortest prepatent periods found were: S. vulgaris, 149–156 days; Triodontophorus spp. and Poteriostomum spp., 63–70 days and trichonemid species 35–42 days.

Two males and one female Aphelenchoides were taken from the rootlets of radish, Raphanus sativus, in December, 1967, in the suburbs of Lucknow (India). They are described as new and are named Aphelenchoides franklini n.sp.

Self insemination appears to be the normal process of sperm transfer in Echinococus granulosus and has been observed in both terminal and subterminal proglottids of worms from dogs.

Cross fertilization between adjacent proglottids or between proglottids of different strobila was not observed.

In some instances, the genital pore was found occluded by a ‘plug’ of material which may represent an antige–antibody precipitate.

The implications of self-insemination in relation to in vitro studies and to the genetics of ‘strain’ production in the genus Echinococcus are discussed.

Experimental studies in mice have shown that with single sex female infections of S. mattheei there is a slow maturation of the worms with evidence of incomplete parthenogenesis; at 9 weeks no eggs were produced but at 17 weeks there was an average of 500 eggs per mouse. These were all non viable. Under similar conditions S. mansoni females failed to produce eggs.

When the females of S. mattheei were paired with males of S. mansoni, the females reached full maturity and produced large numbers of eggs typical of their own species-many of the eggs were non viable but some contained active miracidia.It is considered that this is an example of parthenogenesis and not hybridisation. Cross specific pairings of schistosomes must occur frequently in man particularly with S. haematobium, S. mansoni and S. mattheei and this phenomenon could be of considerable clinical, epidemiological and biological significance. Parthenogenesis in mixed infections probably accounts for the large number of non-viable S. haematobium eggs seen in rectal biopsies, and it may also be important in reducing the transmission potential of schistosomes to man since cross pairing must result in the “sterilisation” of a considerable proportion of the female worms in mixed infections. This phenomenon may also explain the observed reproductive isolation of schistosome species which simultaneously infect the same host.

1. The infective stage larvae of Bunostomum trigonocephalum (Rudolphi, 1808) penetrate the intact skin and undergo skin-lung migration in the mouse and skin-lung-intestine migration in the guineapig. After percutaneous infection in guineapigs, they moult in the lungs to the fourth stage and to the fifth stage in the intestine. Relatively few of them undergo this partial development in the guineapig and they are stunted in growth.

2. In the abnormal hosts, the penetrating larvae cause extensive tissue disorganisation. The histopathology of the skin and lungs is described. There is a cellular reaction to the parasites.

3. In guineapigs, the infective stage larvae reach the lungs after per os infection but they are few in number do no persist for more than six days.

The present paper deals with investigations on the occurrence in Netherlands' fresh water fishes and host specificity of tapeworms belonging to the genus Proteocephalus. The species involved are:

P. tetrastomus (Rudoiphi, 1810) in smelt, Osmerus eperlanus.

P. longicollis (Zeder, 1800) in smelt, Osmerus eperlanus.

P. cernuae (Gmelin, 1790) in pope, Acerina cernua.

P. ocellatus (Rudolphi, 1802) in perch, Perca fluviatilis.

P. macrocephalus (Creplin, 1825) in eel, Anguilla anguilla.

Seasonal cycles were found in P. telrastomus and P. ocellalus; in the latter species this was certainly induced by low winter temperatures.

Experimental infections showed that a high degree of host specificity exists in all species considered. Infections of an alien host were never successful. Two kinds of infections were carried out: (a) feeding plerocercoids (in the intermediate host), coming from a known source, to a number of fishes, belonging to several species including the original host species, and (b) transplanting worms, collected from the intestine of a fish, to the intestines of a number of other fishes, belonging to several species including the original host species.

Notwithstanding the high degree of host specificity, worms may survive for one or two days, but usually in a bad condition, in the intestine of an alien host. Occasionally they survived up to 14 days: e.g. P. tetratomus in Anguilla anguilla. Consequently sometimes dissections of predator fishes or carrion eating fishes may produce dubious host records because actually Proteocephalus from their prey are recorded. We are convinced that P. tetrastomus found in Salmo trutta, Platichihys flesus and Perca fluviatilis originate from Osmerus eperlanus having been eaten by these species.

Additionally cannibalism may be responsible for the fact that large specimens of some fish species, e.g. smelt, are heavily infected with Proteocephalus while they hardly eat any Cyclops, the intermediate host. This is clearly demonstrated by the transplantation experiments, transplanting worms to the proper host.

From the data recorded it is apparent that representatives of the genus Proteocephalus are not harmful to commercially important fishes in the Netherlands. In these fishes natural infection with the proper species of Proteocephalus is low and successful infection with other species, showing a high incidence in less valuable fishes, is prevented by the high degree of host specificity. Additionally worms of the species studied did not injure the tissues of the intestinal wall by the action of their suckers and piercing of the intestinal wall never occurred. Even smelts infected with large numbers of worms-more than 50 in a single 20 cm. specimen-did not show any abnormalities in genital development or in the amount of fat in the body cavity.

Adult Clonorchis sinensis were taken from the bile ducts of infected rabbits and incubated in Ringer's fluid. The soluble metabolic products secreted by the living flukes during incubation were found to include carbohydrate and protein. Enzyme activities of protease, carbohydrases and esterase, but not of lipase, were detected in the samples.

Samples with a nitrogen content of 3 μg/ml or more reacted as antigen in immunodiffusion tests in gel against sera of rabbits infected with C. sinensis or immunised against whole fluke extract.

The demonstration of enzymes in the metabolic products, the reactions of the samples as antigen and the correlation of antigenic activity with the nitrogen content of the samples suggests that the enzymes detected are effective antigens in clonorchiasis, although complete identity was not demonstrated in this study.

The enzymes investigated were those associated with digestion; intracellular enzymes which have less opportunity to elicit antibody production were not investigated.

The work has demonstrated that one of the more important areas of Scotland where Dicrocoelium dendriticum is endemic carried infected colonies of Helicella itala which live in association with the ant Formica fusca. Workers of the ant were shown to acquire typical metacercarial cysts after the ingestion of slime balls, and the cysts gave rise to mature lancet flukes in sheep and hamsters, eggs appearing in the faeces after 56 and 48 days respectively. Higher egg counts were obtained from hamsters to which more cysts were administered. This is the first occasion on which an ant intermediate host has been demonstrated for Dicrocoelium in Britain.

1. Four new species of the genus Diplectanum Diesing, 1858 are described. These are D. cupatum sp.nov. from the gills of both Epinephelus merra Bloch and E. fasciatus (Forskål), D. plectropomi sp.nov. from the gills of Plectropomus maculatus (Bloch), D. summanae sp. nov. from the gills of E. summana (Forskål), and D. vagampullum sp.nov. from the gills of E. merra Bloch.

2. Latericaecum gen.nov. and Monoplectanum gen.nov. are proposed to contain L. pearsoni sp.nov. and M. australis sp.nov. collected from the gills of Sphyraena obtusata Cuvier & Vallenciennes and Sillago ciliata respectively. Calydiscoides gen.nov. is proposed to contain C. australis sp.nov. from the gills of Lethrinus chrystostomu Richardson together with C. difficilis (Yamaguti, 1953) comb.nov., C. duplicostatus (Yamaguti, 1953) comb.nov. and C.flexuosus (Yamaguti, 1953) comb.nov.

3. Lepidotrema angusta (Johnston & Tiegs, 1922) Price, 1937 and L. bidyana Murray, 1931 are redescribed from fresh materials from the type hosts and the generic diagnosis is emended from a study of these specimens, new specimens of L. tenue Johnston & Tiegs, 1922, and named material of L. therapon Johnston & Tiegs, 1922.