60 NEW AND LITTLE-KNOWN LAELAPTIDAE, TROMBICULIDAE AND LISTROPHORIDAE (ACARINA) FROM AUSTRALASIAN MAMMALS. By Robert Domkow. Queensland Institute of Medical Research, Brisbane. (Sixty-two Text-figures.) [Read 29th March, 1961.] Synopsis. Seventeen new species of mites parasitic on Australasian marsupials, rodents and bats are described in the families Laelaptidae, Trombiculid'ae and Listrophoridae. Two previously unlinown males are also described, and additional host and locality data for 23 little known species are given. In the Laelaptidae, nine new species are described : Haemolaelaps quartus, n. sp., from a rat-kangaroo, Aepyprymnus rufescens. New South Wales ; Haemolaelaps ulysses, n. sp., from a ring-tailed possum, Pseudocheirus peregrinus laniginosus, Victoria ; Laelaps breviseta, n. sp., and L. mackerrasi, n. sp., from the allied rat, Rattus assimilis, north Queensland ; Laelaps calahyi, n. sp., from a native mouse, Pseudomys Mgc/insi, Tasmania ; Neolaelaps vitztliumi, n. sp., from a fruit-bat, Pteropiis scapulatus, Northern Territory ; Pneumonyssus dentatus, n. sp., from a marsupial mouse, Antechinus flavipes godmani, and a scale-tailed rat, Melomys cervinipes, north Queensland ; RailUetia australis, n. sp., from the common wombat, Phascolomis mitchelli. New South Wales ; Triclwsui-olaelaps harrisoni, n. sp., from the musk rat-kangaroo, Hypsiprymnodon moschatus, north Queensland. New records are given for Australolaelaps mitchelli, Gymnolaelaps annectans, Haemolaelaps domrowij H. m,arsupialis , Hirstionyssus musculi, Ichoronyssus aristippe (male described for first time), Laelaps assim^ilis, Mesolaelaps antipodianus, M. australiensis , M. handicoota, M. sminthopsis, Neolaelaps spinosus, Peramelaelaps handicoota, Spinolaelaps miniopteri, Tricho-surolaelaps crassipes, T. emanuelae and T. striatus. In the Trombiculidae, two new species are described : Trombicula alicola, n. sp., from a bat, Rhinolophus ■niegaphyllus ; Neotromhicula comata, n. sp., from a marsupial bandicoot, Isoodon macrourus. New records are given for Guntherana andronieda, G. pliilippensis, G. cassiope and G. kallipygos. In the Listrophoridae, six new species are described : Austrochirus m-cmillani, n. sp., from a marsupial bandicoot. New Guinea ; Austrochirus troiiessarti, n. sp., from a marsupial mouse, Antechinus flavipes godmani, north Queensland ; Cytostethuni mollisoni, n. sp., from a rat-kangaroo, Potorous tridactylus, Tasmania ; Cytostethuni clihanarius, n. sp., from a rat-kangaroo, Aepyprymnus rufescens, north Queensland ; Cytostethuni parvuni, n. sp., and C. moschati, n. sp., from the musk rat-kangaroo, Hypsiprymnodon moschatus, north Queensland. New records are given for C. promeces and C. pseudocharact\im, the male of the latter being described for the first time. During the past two years, Dr. J. L. Harrison, at the Institute's Field Station, has been studying the ecology of the small mammals of the Innisfail district in north Queensland, as part of a wider investigation of the epidemiology of leptospirosis in that area. It has been an integral part of this work that collections of ectoparasites have been made from the mammals brought into the laboratory, the result being a very large collection, which has come to me for study. It has included numerous new species, some of which are described here as a preliminary to a distributional analysis of the material. The opportunity has also been taken to include a number of other new species and new host and distributional records in these families, based mainly on material received from Mr. J. H. Calaby, C.S.I.R.O. Wildlife Section, Canberra, and Dr. Bruce McMillan, School of Public Health and Tropical Medicine, Sydney. Family LAELAPTIDAE. The family is taken in the sense of Vitzthum (1940-43), and the genera and species are arranged alphabetically. Proceedings or the Linnean Society of New South Wales, 1961, Vol. Ixxxvi, Part 1.