Seven species of trypanosomes are known, of which Trypanosoma binneyi from Ornithorhynchus anatinus, T. thylacis from Thylacis obesulus, and T. hipposideri from Hipposideros bicolor albanensis are new. These are the first trypanosomes to be described from a monotreme, a marsupial, and an insectivorous bat in Australia. Six species of haemogregarines are known, of which Hepatozoon dasyuroides from Dasyuroides byrnei and H. pseudocheiri from Pseudocheirus laniginosus are new. One species of Hepatocystis is known from flying foxes, and one species of Polychromophilus from insectivorous bats. Four species of Babesia are known, of which B. thylacis from Thylacis obesulus is new. Four species of Theileria are known, of which Th. ornithorhynchi from Ornithorhynchus anatinus and Th. peramelis from bandicoots are new. The ox is the only domestic mammal harbouring sporozoan blood protozoa, three species being known, of which two are certainly pathogenic. Blood parasites, which appear to be related to bacteria or viruses, occur in cattle, rodents, and bandicoots. These include species of Anaplasma, Haemobartonella, and Eperythrozoon. Spirochaetes belonging to the genus Borrelia occur in the blood of cattle, rodents, kangaroos, and bandicoots.

Adult Angiostrongylus cantonensis live in the pulmonary arteries. Unsegmented ova are discharged into the blood stream, and lodge as emboli in the smaller vessels. First-stage larvae break through into the respiratory tract, migrate up the trachea, and eventually pass out of the body in the faeces. Slugs (Agriolimax laevis) act as intermediate hosts. Two moults occur in the slug, and third-stage larvae appear about the 17th day. The larvae remain within the two cast skins until freed in the stomach of the rat by digestion. They then pass quickly along the small intestine as far as the lower ileum, where they leave the gut and become blood-borne. They congregate in the central nervous system, and have been found there 17 hr after ingestion. The anterior portion of the cerebrum is the most favoured site, and here the third moult takes place on the sixth or seventh day and the final one between the 11th and 13th days. Young adults emerge on the surface of the brain from the 12th to 14th day, and spend the next 2 weeks in the subarachnoid space. From the 28th to 31st days they migrate to the lungs via the venous system, passing through the right side of the heart to their definitive site in the pulmonary arteries. The prepatent period in the rat usually lies between 42 and 45 days.

L. sericata, L. cuprina, Ch. rufifacies, C. stygia and C. augur have been bred through many generations in captivity. These flies were bred in artificial light as well as in sunlight. Inbreeding had no effect upon activity, fecundity or length of life.A diet of protein is necessary for the maturation of ova but not of spermatozoa.Oviposition is not strictly associated with a suitable larval environment, but is more in the nature of a response to a tactile stimulus. Copulation appears to provide an essential stimulus for oviposition.No evidence of parthenogenesis has been obtained and unfertilised females did not lay eggs.The maximum oviposition observed was 3,171 ova by a hybrid Lucilia. This fly lived 94 days.A total oviposition of 2,373 ova was observed in a L. sericata. Both parent flies lived 77 days.The number of ova a fly can produce at one time is dependent on its size and thus on the amount of food obtained in the larval stage.The sex-ratio for Lucilia is very close to 1 : 1. Starvation in the larval period did not have a marked effect on the sex-ratio.It is possible to cross the two closely related species of Lucilia, and the cuprina characters appear to be dominant. It is unlikely that this cross occurs in the field.

Trypanosomes are known from tortoises, a gecko, and skinks, Trypanosoma phylluri from Phyllurus platurus, and T. egerniae from Egernia striolata and E. cunninghami being new. There is an old record of a trypanosome in a snake, but the organism has not been rediscovered. Haemogregarines are common in all groups. Names had already been given to 2 from tortoises (one of which is regarded as a synonym), 4 from lizards, and 10 from snakes in Australia. Three species described from snakes in Asia have been added, and 15 new species are described from the following type hosts : Haemogregarina heteronotae from Heteronota binoei; Hg. palmeri from Physignathus lesueurii; Hg. taeniolati from Sphenomorphus taeniolatus; Hg. cunninghami, Hg, egerniae, and Hg. obscura from Egernia cunninghami; Hg. johnstoni from Varanus varius varius; Hg. breinli and Hg, gilruthi from Varanus tristis orientalis; Hg. stegonoti from Stegonotus plumbeus; Hg. boigae from Boiga fusca; Hg. australis and Hg. eidsvoldensis fom Pseudechis australis; Hg. denisoniae from Denisonia pallidiceps; Hg. aspidomorphi from Aspidomorphus harriettae. Two species of Plasmodium are known from lizards, P. egerniae from Egernia major major being new. The genus Haemocystidium is revived, one species being recognized in freshwater tortoises and one in geckos. Pirhemocyton has been found in two species of geckos and a carpet snake.

SUMMARY Sixty strains of 11 viruses were isolated from 25,901 mosquitoes of 32 species collected at Mitchell River Mission, Cairns and Normanton in 1960 and 1961. The viruses, the local prototype strains and the mosquito species, geographical location and year of repeatable isolations, were: Group A: Sindbis (MRM39) from Culex annulirostris and Aedes normanensis at Mitchell River (1960) and Cairns (1961); AMM2021 (N544) from Anopheles amictus amictus and Culex bitaeniorhynchus at Normanton (1961). Group B: Murray Valley encephalitis virus from C. annulirostris at Mitchell River (1960 and 1961); Kunjin (MRM16) from C. annulirostris at Mitchell River (1960); Kokobera (MRM32) from C. annulirostris at Mitchell River (1960 and 1961); Edge Hill (C281) from Aedes vigilax and C. annulirostris at Cairns (1961); Stratford (C338) from Ae. vigilax at Cairns (1961). Koongol group: Koongol (MRM31) from C. anulirostris at Mitchell River (1960) and Normanton (1961); Wongal (MRM168) from C. anulirostris at Mitchell River (1960 and 1961). Ungrouped: MRM1 (found resistant to ether and sodium desoxycholate) from C. anulirostris at Mitchell River (1960); Mapputta (MRM186) from Anopheles meraukensis at Mitchell River (1960) (not reisolated). C. annulirostris was the commonest mosquito collected (12,124) and the source of 44 of the virus strains. Eight of the viruses appear to be new. One (Murray Valley encephalitis virus) has previously been isolated from man in Australia and two (Sindbis and AMM 2021) from mosquitoes elsewhere.