1. The pathology of Stephanofilaria kaeli lesions is described from the legs of cattle in Malaya.

2. The possible modes of transmission of the parasite are discussed based on the pathology.

3. A comparison is made between the pathology of Stephanofilaria kaeli lesions and those produced by other species of Stephanofilaria.

Of the 1,090 hake, Merluccius merluccius (L.), examined for Aporocotyh spinosicanalis, 323 were infected. Only adult flukes were found and these in the heart and bulbus arteriosus only; this habitat specificity and the apparent strict specificity of the fluke to hake are briefly discussed. The occurrence of from 1 to 5 flukes in each infected fish was common but up to as many as 60 were recorded. The incidence of infection is high in hake from shallow water in some areas to the west of Scotland; a particularly high incidence was found in the Minches and Sea of the Hebrides area. The incidence of infection was very low to the southwest of the British Isles and off Hartlepool in the North Sea; only 1 of 82 fish from these regions was infected. The possible use of A. spinosicanalis as a biological tag is discussed. A significant difference was found in the incidence of infection in hake of different length groups, the most heavily infected being those measuring 26 to 55.9cm.; small hake (25.9 cm. and below in length) from shallow water showed a low incidence of infection. Speculations are made on the possible course of the life-cycle of A. spinosicanalis. There was no significant difference in the distribution of the fluke in male and female fish and no obvious effect on the condition of the host was observed.

The results are given of the preliminary screening of many organic compounds and pesticides and of a few inorganic compounds on the eggs of T. hydatigena and T. ovis.

Over fifty of these chemicals had little, if any, effect on activity or on hatching, the majority of the others had only an insignificant effect. Moreover, many of the most effective were hindered by the protection of proglottids. Furthermore, some could not be used in practice.

1. Two new species (Postharmostomum ntowi and Eptsthmium ghanense) and one previously described species (Episthmium africanum) of digenetic trematodes are recorded from the domestic fowl in Ghana.

2. A key has been provided for identification of all the species of Postharmostomum occurring in chickens.

3. Episthmium africanum is recorded for the first time from the domestic fowl.

1. Haplorchis taichui H. yokogawai and Stictodora manilensis are recorded for the first time in India from dogs.

2. H. helerophyes from Indian cats are very much smaller than those recorded from dogs.

3. A technique has been described to study the chitinous armature of the gonotyl in heterophyid trematodes.

During the last two decades a number of species have been described in the already large genus Oxyspirura Drasche in Stossich, 1897. Twenty four new species have been described from India alone ; 2 by Singh (1948), 9 by Ali (1960), 4 by Rasheed (1960), 8 by Sultana (1964) and one by Siddiqi and M. S. Jairajpuri (1964). Recently, Oliveira Rodrigues (1962, '63) added 5 species from Brazil and Barus (1963, '65) 2 species, one from U.S.S.R. and the other from Czechoslovakia.

A survey of avian nematodes of Uttar Pradesh in India and Shagunu, Northern Nigeria yielded a number of worms from the orbital cavities of different birds. They represent 14 unidentified species of Oxyspirura and are here described as new.

All measurements are in millimetres unless otherwise stated.

1. The filarial worm Brugia patei was brought to London from East Africa in the larval stage developing in Mansonia mosquitoes. Subsequent transmission to domestic cats was possible in London through a laboratory colony of Mansonia uniformis and the worm was very infective to this species of mosquito. The worm was much less infective to Aedes togoi and Anopheles gambiae.

2. Subsequent passage of the worm through Aedes togoi has increased its infectivity to this species of mosquito. The infection rate has risen from 43·6% in females of A. togoi fed on the cat original- ly infected by larvae from Mansonia mosquitoes, to 59·2% in females fed on a cat containing the first generation of worms to pass through A. togoi, to 79·1% in females fed on cats containing the second generation of worms to pass through A. togoi, to 86·7% in females fed on cats containing the third generation of worms to pass through A. togoi, to 89·8% in females fed on cats containing the fourth generation of worms to pass through A. togoi.

3. The distributions of infective stage larvae in female mosquitoes were negative binomial distributions. These were related to the distributions of microfilarial intake immediately after infection which were also negative binomial. From one generation of worms passed through the new mosquito host to the next the mean and the k value of the negative binomial of the infective stage larvae approached the same parameters for the distribution of microfilarial intake. By the fourth generation of worms passed through A. togoi the distributions of microfilarial intake and infective stage larvae developing in A. togoi were similar, suggesting close adaptation to the new mosquito host. A similar relation between these distributions was found originally in Mansonia. There were however considerable differences in these distributions between the two species of mosquito.

4. The experiment extended over a period of 6 years. The change in infectivity did not appear to be related to the microfilarial density, age of infection, or sex, in the mammalian host. Neither could it be related to the genetics of susceptibility in the mosquito, nor to mosquito culture techniques, nor to mosquito mortality.

5. It is concluded that the observed change in infectivity is best explained by a change in adaptation of the worm to the new intermediate host by selection within the mosquito of those microfilariae adapted to it. No major change in infectivity to the original intermediate host, Mansonia, was found during the experiment.

6. These findings are examined with reference to changes in adaptation to mosquito hosts in the history of Bancroftian filariasis.

Single experimental infections of 8 to 12 week old calves with 200 to 15,000 metacercariae are described. It is shown that as the level of metacercariae infection rises the numbers of fluke reaching and persisting in the bile ducts fall. In the higher infections the majority of the flukes are trapped and eliminated in the parenchyma and clinical disease does not develop. In lower infection levels the majority of the flukes reach the bile ducts and clinical disease develops.

Experiments are described in which calves were given 200 metacercariae and then a challenge infection of 300 metacercariae. When the challenge infection was given 3 weeks after the initial infection a small but insignificant reduction in take was observed. When the challenge infection followed 18 weeks after the initial infection, the existing infection was eliminated. This phenomenon is referred to as an “acquired self cure”.

Investigations of acquired immunity to Fasciola hepatica in calves, sheep and rabbits are described. With injections of extracts of imma- ture parasites retarded growth of the challenge infection was observed between the 6th and 7th week. Following a previous experience of a natural infection or viable fluke implants, retardation and reduced take of the challenge infection were observed. Considerable individual variation was present and the level of significance between treatment and control groups was low.

1. Ten species of Capillaria are recorded from eight species of British birds. C. blomei from the pheasant and partridge and C. exilis from the rook are new host records.

2. The identity of C. reseda and the systematics of C. blotnei, C. bursata and C. caudinflata are discussed in the light of observations made upon material in the collection.

The material of this study consists of three monogenetic trematodes which were collected in mid August, I960 from the urinary bladder of Rana (Ptychadena) oxyrhynchus caught in Kumba, the Cameroons (West Africa). Mr. F. R. N. Pester, F.I.S.T., of the Department of Parasitology, London School of Hygiene and Tropical Medicine kindly forwarded the material to the writer for identification.

The specimens are all identical, belonging to a new species of the genus Polystoma Zeder, 1800 which is described herein as Polystoma Prudhoei sp. nov. in honour of Mr. S. Prudhoe of the Department of Zoology, the British Museum (Natural History) for his unfailing help and advice.

1. The anatomy of Apharyngostrigea (Apharyngostrigea) simplex (Johnston, 1904) new comb, from young cattle egrets is described in detail, involving the reconstruction of its internal organisation from serial sections.

2. The relationships of the species within the genus Apharyngostrigea Ciurea, 1927 is discussed using the method of Numerical Taxonomy by Sneath and Sokal (1902). It is found that the original genus can be split into two genera. The genus Apharyngostrigea comprises two subgenera; Apharyngostrigea (Apharyngostrigea) n. subgen. and A. (Brasiliana) n. subgen. made up of seven species groups. The generic diagnosis of Apharyngostrigea Ciurea, 1927 and Chaseostrigea n. gen. are given as well as a key for separating the species of the genus Apharyngostrigea.

Eight species of the nematode genus Capillaria Zeder, 1800 are described from fifteen species of avian hosts. All but two of the host records are new for the species concerned. One species, C, longifila, is fully described for the first time. The results are discussed in relation to the systematics of avian capillariids.

Williams and Chaytor (1966) reported the presence of encysted strigeid trematode larvae on the muscles and liver of Epiplatys sexfasciatus and E. senegalensis collected from a stream at Hastings, Sierra Leone. Out of 253 fishes examined 89 or 35% were infected with the parasite.

The parasites when fed to day-old chicks or cattle egrets gave rise to adults which were identified as Posthodiplostomutn nanum Dubois, 1937.