1. Parvatrema homoeotecnum sp.nov. from the oystercatcher, Haematopus ostralegus occidentalis Neumann at Aberystwyth is described and compared with other species of the genus.

2. The life cycle of this species is unique. The larval stages occur in the gastropod, Littorina saxatilis (Olivi) subsp. tenebrosa (Montagu) and include germinal sacs which have a structure and development similar to an adult digenean. There are no free-living stages and only one intermediate host.

3. The significance of this unique life cycle is discussed.

4. The family Gymnophallidae Morozov, 1955, is reviewed. Emended definitions are given for the family, subfamilies and genera. Keys, diagnostic features and brief notes of the species are included.

I am very grateful to Dr Gwendolen Rees, who suggested the investigation which led to the discovery of this species, for her advice and indispensable assistance throughout the work and the preparation of this paper. I am also grateful to the late Professor T. A. Stephenson for his interest and for the provision of working facilities; to Mr W. A. Ballantine, Mr A. H. Clarke, Jr., Mr C. Curtis, Miss G. P. F. Evans, Dr V. Fretter, Professor L. A. Harvey, Mr D. H. Jones and Dr J. Lewis who sent me specimens of Littorina saxatilis; to Professor R. M. Cable and Emerit. Professor G. R. La Rue for helpful suggestions; to Mr J. R. Hirst and Mr D. Hemingway Jones for photographic and technical assistance and to the Department of Scientific and Industrial Research for a grant which made the work possible.

Koga (1922) recorded for the first time the occurrence of metacercariae belonging to the genus Phyllodistomum Braun, 1899, in the freshwater shrimp, Palaemon nipponensis from Japan. Later Yogota (1922), Hirata (1928) and Asada (1928) recorded that shrimps in Japan were infected by larvae of several species of Phyllodistomum.

The genus Azygia was erected by Looss (1899) for Fasciola tereticollis Rud. (1802) ( = Fasciola lucii Mueller, 1776) from the stomach of Esox lucius in Europe. Other species of the genus were described a few years later, namely, Azygia loossi by Marshall & Gilbert (1905) from Micropterus salmoides, Lucius lucius and Amia calva; A. volgensis by von Linstow (1907) from Lucioperca sandra; A. sebago by Ward (1910) from Salmo sebago and A. bulbosa, and A. acuminata by Goldberger (1911) from Amia calva.

Experiments on the larval development of Fasciola gigantica carried out under natural conditions have shown that at temperatures of 16° C. or less the rediae did not produce cercariae. The first-generation rediae, developed from the sporocyst, and all the rediae of subsequent generations produced only daughter rediae and did not change over to the production of cercariae as long as the low temperatures of the cold season lasted.

As soon as the cold season ended and the temperature of the water in the aquaria containing the infected snails rose to a mean maximum of 20° C. all the rediae switched from redial to cercarial production.

The morphology of the adult blood fluke Schistosoma edwardiense sp.nov. from Hippopotamus amphibius L. is described and compared with that of other species of Schistosoma.

I wish to acknowledge the receipt of a research grant from Makerere University College towards expenses incurred during this work. I should like to thank Captain F. Poppleton, Warden of the Queen Elizabeth National Park, Dr R. M. Laws, Nuffield Unit for Tropical Animal Ecology, and Dr W. M. Longhurst, University of California, for helping me to get specimens from the hippopotami, also Mr L. Rugema, histologist, for sectioning the worms.

1. The distribution of acid and alkaline phosphatases in the hepatopancreatic cells of the molluscan host of Echinoparyphium sp. and in the redia and cercaria of this trematode has been studied.

2. There is a heavier concentration of acid phosphatase in the hepatopancreas of infected snails than in uninfected snails.

3. No acid phosphatase is present in the bodies of the rediae or cercariae but this enzyme is present in the contents of the redial caeca.

4. Alkaline phosphatase activity is greater in the hepatopancreas of infected snails than in uninfected snails.

5. Alkaline phosphatase is present in the tissues of the rediae and the cercariae, especially in the fully developed cercariae.

6. It is suspected that the increase in acid and alkaline phosphatases in Helisoma trivolvis infected with Echinoparyphium redia is correlated with the breakdown of glycogen by the parasite.

This research was made possible by Grants E-3443, E-3443C1, and AI 3443–03 from the Institute of Allergy and Infectious Diseases, National Institutes of Health, U.S. Public Health Service. The author is grateful to Mr Randall W. Snyder, Jr., School of Medicine, The University of Virginia, for technical assistance.

1. The different lipid fractions in Gastrothylax crumenifer after starvation for 8–10 hr. have been estimated.

2. The percentages of different fractions in the total ether extract were found to be: acetone-insoluble material 16, unsaponifiable matter 25, saturated fatty acids 5, unsaturated fatty acids 20, glycerol 2 and unidentified lipids 32.

3. The above percentages of lipid fractions have been compared with the corresponding data for different parasites obtained by other workers.

A method is described by which viable sporozoites of the sheep parasite, Eimeria arloingi, may be obtained in sterile solution and free of any extraneous vegetable matter. Faeces are washed through metal sieves and the oocysts separated by a gravity floatation technique. The oocysts are sterilized and floated free of any remaining faecal debris in a solution of sodium hypochlorite. Sporulation is induced by constant aeration in water. Excystation is effected by incubating firstly under an atmosphere of carbon dioxide and secondly in a solution of trypsin and sheep bile.

I wish to thank Professor H. R. Carne for encouragement and advice, and Mr R. F. Jones for skilful technical assistance.

1. Examination of dividing trophozoites of E. invadens revealed that the peripheral granules did not contribute directly to the formation of chromosomes. Material for the chromosomes seemed to be derived from the karyosome and the perikaryosomal particles. No centrioles and spindle mechanism were noticed.

2. The nucleus showed Feulgen-positive material at all stages; in the interphase the reaction was faint because of the poor staining of the karyosome and widely dispersed perikaryosomal particles. The intensity of the staining reaction increased with the onset of division and continued so till late anaphase.

3. Nuclear division in the cyst was found to be different from that of the trophozoites and involved the formation of a typical spindle.

4. Karyosomes of the nuclei of the uni-, bi-, tetra-nucleate cysts were all positive to Feulgen staining.

5. Observations on amoebae undergoing cytokinesis showed that the process of division supports the amoeboid movement theory of cleavage put forward by Chalkley (1935, 1951).

Thanks are due to Dr P. Tate for constant guidance and encouragement during the course of this work and to Dr E. W. McConnachie for kindly giving the cultures and for critically reading through the manuscript. The work was carried out during the tenure of a Royal Society and Nuffield Foundation Commonwealth Bursary.

The incidence and prevalence of coccidia have been studied in populations of free-living red kangaroos, Megaleia rufa, and grey kangaroos, Macropus canguru, in four geographically distinct areas in Australia.

Two new species of Eimeria—E. wilcanniensis and E. toganmainensis—are described from M. rufa, and five—E. cunnamullensis, E. gungahlinensis, E. purchasei, E. kogoni, and E. hestermani—from M. canguru.

The incidence of coccidia ranged from 6 to 14% in populations of M. rufa and from 26 to 70% in M. canguru. The susceptibility of the animals to coccidia was analysed in relation to the tibia length. Red kangaroos with tibia approximately 360 mm. long and corresponding to an age of about 12 months were found to be most susceptible. No clinical cases of coccidiosis were seen in the field.

Special thanks are due to the owners or managers of the properties on which the kangaroos were sampled; to members of the staff of the Regional Pastoral Laboratory ‘Gilruth Plains’ for their assistance in sampling, and to Messrs E. R. Hesterman, C. Kogon, and D. Purchase, who assisted in the field and the laboratory. Three species of Eimeria have been named after them in acknowledgement of their work. Messrs B. V. Fennessy and J. H. Calaby of this Division kindly read the manuscript.

I wish to thank Dr G. B. Sharman for his permission to work with captive kangaroos in Canberra, and Mr E. Slater who took the photographs.

Uninfected erythrocytes of Rana boyli, in the presence of glucose, utilized 214μ1. O2/hr./108 cells. Cells infected with Haemogregarina boyli increased oxygen consumption approximately 12% for a 10% rate of infection. Alkaline phosphatase and zymohexase, but not acid phosphatase, urease, lipase or peroxidase, were demonstrated in the parasites by cytochemical means.

Cytamoeba bacterifera from urodeles (Batrachoseps attenuatus, Aneides lugubris, A. flavipunctatus and Dicamptodon ensatus) show a thin peripheral ring of DNA and a less definite, heterogeneous central portion after Feulgen treatment; toluidine blue reveals a similar configuration. Exposure to DNA-ase and RNA-ase, followed by toluidine blue and Feulgen treatment, substantiates the localization of DNA; RNA is present in small quantity and restricted to the periphery of the parasite.

Mitochondria (2–5μ long rod-shaped, central bodies) can be detected with Janus Green B, and osmium tetroxide yields a dark central mass of rods and granules as well as peripheral granules; Sudan Black IV is without action. Zymohexase and acid phosphatase can be detected by cytochemical means, but peroxidase, lipase, urease and alkaline phosphatase were not noted.

From the evidence presented, C. bacterifera is considered a living entity and is tentatively relegated to the Piroplasmida.

The writer would like to express his appreciation to Dr R. S. Bray of the American Foundation for Tropical Medicine, Harbel, Liberia, for his counsel and suggestions.

Lobochona insularum sp.nov., a collar ciliate (Chonotrichida), an ectocommensal on the pleopodal bristles of a gribble from Hawaii, is described. L. insularum differs from the previously described chonotrichidan ectocommensals of the gribbles, L. limnoriae on Limnoria lignorum and Lobochona prorates on Limnoria tripunctata, in the outlines of the body and of the marginal lappets of the collar.

This work was supported by a grant from the National Science Foundation. Various facilities were made available by the Allan Hancock Foundation of the University of Southern California.

Acknowledgement is given to Dr Bayard H. McConnaughey, who discovered the organism and prepared the slides.

The large and small forms of Tylenchorhynchus macrurus are distinguished as separate species. The large form becomes T. icarus and differs from the small form, T. macrurus in the greater number of annules on the female tail, longer stylet and slimmer body. The oxygen consumption of both species is similar when assessed in terms of body surface area. Soil samples from the field indicated that (a) greatest concentrations of T. icarus occurred at about 5 cm. depth, (b) few occurred below 24 cm., the depth of the top soil, and (c) numbers of T. icarus in the top 5 cm. of soil decreased during dry periods and increased after rain. T. icarus migrates to the wet end of a moisture gradient and has maximum mobility in soil at a moisture content corresponding to field capacity and at 20° C. T. icarus survived osmotic pressure equivalent to 1 m urea for 4 days. Their oxygen consumption increased with increasing osmotic pressure but in 1 m urea there was a decline which was even more pronounced in 2 m urea. Of a population of T. icarus 35% survived for 32 weeks in soil with plants. In damp sand at 10° C, oxygen consumption was steady for 32 weeks but after 48 weeks the nematodes were dead. It is suggested that the free-living stages of plant parasitic nematodes have similar migratory habits.

1. A method of trapping small mammals has been described and Apodemus sylvaticus, Clethrionomys glareolus, Microtus agrestis and Sorex araneus were captured. The method of trapping has been discussed.

2. A survey of the endoparasites found in the four host species has been produced. The two more common hosts and four of their parasites have been chosen for more detailed study.

3. The infection levels of the parasites in the two hosts have been calculated and compared with other published data.

This work was carried out during the tenure of a Department of Scientific and Industrial Research Studentship. My thanks are due to Dr H. D. Crofton for his very helpful supervision and criticism and to Professor J. E. Harris, F.R.S., in whose department this work was done, for the facilities provided.

From 24 May to 4 July 1961 about 12,000 roach, Rutilus rutilus (L.), died in a lake at Brynmill Park, Swansea, South Wales. Even this high figure may be an underestimate of the actual mortality rate as it is based entirely on extractions of dead fish from the surface waters by members of the Brynmill and District Angling Club, who used landing nets from the shore only, although at fairly regular intervals. The daily counts of dead roach are represented on a histogram (Text-fig. 1). It is also of interest that in the early summer of 1961 large numbers of roach succumbed in other regions of the British Isles; about 30,000 died in the River Trent, Derbyshire, and 3000 in the lake in St James's Park, London. Newspaper reports in both localities attributed the cause to a deficiency of oxygen. For the outbreak in South Wales, however, similar reports suggested that ‘white spot disease’ caused by the ciliated protozoan Ichthyophthirius was responsible for the mortality.

The successful rearing of Amblyomma sparsum, using rabbits as larval and nymphal hosts and either sheep or tortoise for feeding adults, is described and details of the duration of the various stages are given. The life cycle of this tick is compared with that of A. variegatum and A. nuttalli.

The authors are grateful to the Director of the Coryndon Memorial Museum, Nairobi, for the loan of a Leopard Tortoise, and to the Directors of the East African Veterinary Research Organization and of the Veterinary Services, Kenya, for permission to publish this note.

Six new species of cestodes from birds have been described. These are: Ophryocotyle indicus from the Rufous Babbler, Turdoides subrufus; Biuterina dicruri from the Grey Drongo, Dicrurus leucophaeus longicaudatus; Choanotaenia tandani from the Himalayan Whistling Thrush, Myiophoneus caeruleus temminckii; Choanotaenia picusi from the Scalybellied Green Woodpecker, Picus squamatus; Panuwa stylicirrosa from the Little Scalybellied Green Woodpecker, Picus xanthopygaeus; and Anoncotaenia indica from the Rufous-bellied Niltava, Muscicapa sundara.

1. A local population of Gammarus pulex, infected with Heliospora longissima and Rotundula gammari, was found to have an intracellular developmental stage.

2. Experimental infections of G. pulex were made with the two species of gregarines. In the case of R. gammari infections, large numbers of intracellular developmental stages were found.

3. The taxonomic relationship of the genera Cephaloidophora and Rotundula is discussed.

Thanks are due to Dr P. Tate for constant encouragement and guidance during the course of this work and for the many helpful suggestions in the preparation of the manuscript. Thanks are also due to Mr D. W. T. Crompton for kindly giving me the infected material. The work was completed during the tenure of a Royal Society and Nuffield Foundation Commonwealth Bursary.