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Calves infected with a sporozoite suspension of the Ikeda strain of Theileria sergenti were examined in attempts to detect the schizont stage. A suspension equivalent to the contents of 70-200 ticks was inoculated subcutaneously into 10 splenectomized calves. Schizonts and micromerozoites were found in the prescapular lymph nodes of 5 calves about 8 days after the sporozoite inoculation. Schizonts detected at the time of nuclear division had large and diffuse nuclei, and many of the schizonts were very large and extracellular in lymph node smears. The schizonts were also detected by the direct fluorescent antibody staining.

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Adult Haemaphysalis punctata (Canestrini and Fanzago 1877) collected from an area of rough grazing at Mynydd Mawr, Aberdaron, North Wales, transmitted Theileria recondita (Wales); field-collected nymphs failed to transmit this parasite. Following adult tick infestation, piroplasms were first observed in the blood of splenectomised infested sheep 8 days after tick attachment; the parasitaemia lasted 9 days. The parasite can also be transferred by syringe passage of blood from splenectomised to normal sheep and vice versa. Parasitaemias were higher and of longer duration in splenectomised animals. A rise in parasitaemia was detected in a splenectomised ewe after parturition, 19 months following blood-transmitted infection from which it had recovered clinically. The morphometrics of the piroplasms of T. recondita (Wales) were investigated; the rod and the ring forms were the most common. The mean length of the rod form was 2.09 microns and the mean diameter of the ring form was 1.22 micron.

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Hipposideros larvatus of Thailand are parasitized by two new Haemosporidia : a) Nycteria brucechwatti n. sp. can be differentiated from all other Nycteria species by the schizonts which are the largest in the genus and by the absence of accessory chromatin dots in the gametocytes; Biguetiella minuta n. g. n. sp. has very small intra-hepatocytic schizonts (less than 15 micron) and gametocytes of the "falciparum" type. These two species are considered as vicariant forms of parasites of Miniopterus, namely Polychromophilus and Bioccala. The subgenus Bioccala is raised to genus status and problems related to the study of polyparasitic infections of the same host are discussed.

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It is currently thought that the following species or sub-species of Theileria occur in cattle in southern Africa: Theileria parva parva (East Coast fever), Theileria parva lawrencei (Corridor disease), Theileria parva bovie (Rhodesian theileriosis), Theileria mutans proper (transmitted by Amblyomma species), so-called Theileria mutans (a non-pathogenic species transmitted by Rhipicephalus appendiculatus, possibly identical with Theileria taurotragi) and Theileria velifera. The parasites can be differentiated on serological, morphological and epidemiological grounds. The four true species are serologically distinct. T. mutans proper and T. velifera show morphological differences from the other two species in some stages of their development. The T. parva group are the only parasites that are commonly pathogenic. Differentiation of the three members of this group is based on differences in the numbers of schizonts and piroplasms present and on differences in the epidemiology of the diseases they cause.

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White nodules containing intracellular ovoid Sporozoans were observed in internal organs (kidneys, liver and gut wall) of cultured Sparus aurata and in the liver of wild Siganus luridus in the gulf of Aquaba in the Red Sea. Nodules consisted of parasitised hypertrophic macrophage-like cells enclosed in a well-defined collagenous fibrous capsule. These parasites are evidently the cystozoite stage of a haemogregarine.

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The schizogony of Polychromophilus was partially known by the findings of Schingarew, Mer and Goldblum who demonstrated microschizonts in the reticulo-endothelial tissue. The present work completes these data by showing the presence of macroschizonts in the lungs of both African and European species. These schizonts are characterized by their large size, the hypertrophy of the host cell and its nucleus and the evolution of the parasite apparently slow when young, becoming rapid later.

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A checklist is given of the 89 named species of the gregarine family Lecudininae, exclusive of the 42 named species of the genus Lecudina (phylum Apicomplexa, class Sporozoea, subclass Gregarinia, order Eugregarinida, suborder Aseptatina). The list includes also the synonyms, host names, locations in hosts, known geographic distributions of the species, as well as key references. Another list is given of synonyms, lapsi calami, nomina nuda, etc., associated with the genera. A new genus, Paraophioidina g.n., with type species, Paraophioidina haeckeli (Mingazzini, 1891) and a new species, Lankesteria ormieresi sp. n., are described. There are also new combinations in the genera Bhatiella, Ancora, Monocystella, Ascocystis, and Paraophioidina.

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Pneumocystis jiroveci n. sp. from humans is redescribed, including the trophozoite precyst, cyst, intracystic bodies, and empty cyst. The morphology, biology, and physiology of this organism are compared with those of P. carinii from rats. Drug-induced immunosuppression produces similar disease patterns in both hosts, but several other pathogenic mechanisms seen in man have not been reproduced in rats. In most humans, immunity terminates infection and carriers are few; but in rats, immunity is generally associated with latent infection. The factors influencing the growth of Pneumocystis spp. in hosts varying in immune potential are reviewed and indicate that immunity is multifaceted, depending on the presence of plasma cells, antibody, T lymphocytes, macrophages, and probably complement. A deficiency in only a single component may give rise to clinical disease. Infection patterns in humans and pneumocystosis in mammals are reviewed. No evidence of the biologic identity of organisms from several hosts has been found. Serologic evidence concerning the distinction between Pneumocystis of rat and human origin is reviewed. These two forms should be regarded as deparate species, and forms from other hosts should tentatively be regarded as distinct.

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Two new species of Davisia were identified in the urinary bladders and kidney tubules of 2 species of marine fish. D. anoplopoma was found in Anoplopoma fimbria from southern and central California. D. pectoralis was recorded from Coryphaenoides pectoralis from northern California. We have distinguished between Davisia species whose lateral appendages are "solid" and those which contain a cavity in their lateral appendages. Our species belong to the latter category. We believe the lateral appendages of "hollow" species are extensions of the spore body and not, as sometimes pictured, independently attached.

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