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Summary is absent.

The paper contains a brief history and results of studies of the systematics, fauna, distribution, biology, medical importance and control of sand-flies in the USSR during the post-revolutionary period.

Studies of different groups of the gamasid mites (Bregetova, 1946—1967), the valuation of their characters and an analysis of the literature allow the following conclusion to be drawn. For the erection of a natural system of the gamasid mites it is first necessary to analyse the main directions and principal trends in the evolution of the whole group and its separate branches and the secondly to find out the degree of morphological and biological isolation of large groups and to substantiate their taxonomic relationships. The only way to understand the variety within the group of the gamasid mites is by the elucidation of the main directions of their evolution during the ontogenesis, i. e. postembryonic development. In allied forms the order of appearance of densely sclerotized shields during the ontogenesis, their topography and the number and relative sizes were found to be identical. The analysis of these changes in addition to ecological data permits the substantiation of allied groups of family status. (Fig. 1 — scheme of the changes in the structure of the dorsal surface in the gamasid mites. Vertical rows: larvae, protonymphs, deutonymphs and adult mites. Horizontal rows: families).

Listrophorus leuckarti has been recorded hitherto only from 12 species of 7 genera of rodents. Studies of fur mites of the genus Listrophorus, found on rodents of 5 genera, have shown that this species occurs only on voles (Arvicola, Microtus, Clethrionomys). Other rodents which were investigated (Apodemus and Rattus) are parasitized by mites of another species of this genus not yet described. The adults of L. leuckarti are described in detail. L. leuckarti morphologically resembles Listrophorus mites which parasitize muskrats. Certain similarities in the biology of both species have been observed in the adaptation of the separate stages to definite parts of the host's body.

Ixodes maslovi sp. n. described on male (holotype) and female (allotype) was found on plants in the vicinity of Khabarovsk. The species belongs to the subgenus Monoindex subgen. n. The first segments of palps are fused into a ringshaped organ that is the main morphological character of a new taxon. The holotype and allotype are preserved in the Zoological Institute of the Academy of Sciences of the USSR.

It has been established that hybridization between Ornithodoros coniceps and O. capensis in the laboratory is well possible in both combinations. Observations on the morphology of the hybrid progeny of the first generation have shown that in the larvae maternal characters dominate. Hybrid nymphs and adudlts are intermediate between the parental species. This relates without exception to all the characters which were investigated in the experiments. Hybrid generations are less viable that manifests itself in a sharp increase of the number of individuals of the V^th nymphal stage over the parental individuals. A partial sterility of hybrids is expressed in the reduction of their fertility, in the mortality of more than 50% of eggs in the clutches and in the immaturity of gonads in hybrid females. These data indicate that there is a partial isolation between parental species. However, due to a successful laboratory hybridization the investigated species may be assumed to be closely related in phylogenetic respect and to be comparatively young.

10 species of arthropods were found on muskrat in Byelorussia. Laelaps multispinosus is most abundant (87.6% of all mites found). It was normally specific to the muskrat but was recorded also from water voles. Laelaps muris (index of abundance 0.66), Hyperlaelaps amphibius (0.14) and Haemogamasus ambulans (0.35), while parasitize the water vole, are also rather abundant on the muskrat. This indicates that muskrat may be involved in the circulation of agents of diseases transmitted by the water vole and its ectoparasites.

The mite Ornithonyssus dogieli (Breg.) was shown to be dominant in the above-ground nests of Dyromys nitedula in the vicinity of Alma-Ata. In the nests of these rodents, situated in artificial nests of birds, the mite Haemolaelaps casalis (Berl.) prevails. Hl. casalis is capable of eradicating O. dogieli. Differences in the populations of the gamasid mites in above-ground and underground nests of D. nitedula depend on the microclimate of these nests, food, behaviour of the mites inside the nest and on the nature of relationships between these species.

The information set forth in this paper was acquired during two seasons of 1965 and 1966 in the Voronezh region. In order to determine a physiological age of females of Haematopota pluvialis L. attacking man regular collections were made. In addition to this, experiments were carried out in the laboratory for observations on the effect of full and partial engorgement of females with blood upon the maturation of eggs in ovaries. If a blood portion engorged by females does not amount to 0.3 of the body weight the ovaries do not develop. A blood portion accounting for 0.3—0.6 of the body weight results in a complete maturation only of a small number of eggs (25—40 eggs). If a blood portion engorged increases 1—2 times the body weight 55—114 eggs mature. This quantity, however, is 2 times less than the possible number of eggs judging by the total number of egg tubes. The local population of H. pluvialis has time to lay one clutch of eggs within summer, a part of the population has time to lay two or even three clutches.

Nematodes of the superfamily Mermitoidea were found in females of Leptoconops sp., Culicoides pulicaris and in larvae of C. nubeculosus, C. puncticollis, C. stigma, the circumscriptus group and in C. grisescens. In one of the samples infestation with nematodes was 27.3%. Parasitism by mermices results in the death of the larvae.

The work devoted to the description of three new representatives of Capsalidae belonging to subfamily Megalocotylinae as accepted in Bychowsky's work (1957), as well as the discussion of their systematic status and position. As a result of the work three new genera were established, the diagnoses are following. 1. Sprostoniella gen. nov. Haptor with 17 radiate septs, two of them are divided into three branches and with 21 peripheral depressions. There are two pairs of median hooks. Testes consist of numerous follicles situated into two separate neighbouring groups located behind the ovary. Other characters correspond to diagnosis of subfamily. Type species — Sprostoniella multitestis sp. n. (fig. 1, 4). 2. Megalocotyloides gen. nov. Haptor with five radiate septs and the same number of peripheral depressions. There are three pairs of median hooks. Other characters correspond to diagnosis of subfamily. Type species — Megalocotyloides epinepheli sp. n. (fig. 2, 5). The second species of this genus — M. pseudomarginatus (Br. Hollis, 1958) n. comb. 3. Trilobiodiscus gen. nov. Haptor with three radiate septs and the same number of peripheral depressions. There are three pairs of median hooks. Four large testes are situated by pairs one after another. Other characters correspond to diagnosis of subfamily. Type species — Trilobiodiscus lutiani sp. n. (fig 3, 6).

The paper contains a description of new species, Encotyllabe caranxi sp. nov. and E. latridis sp. nov. (the fam. Capsalidae Baird, 1853) from fishes of the Great Australian Bay and the Tasman Sea. E. caranxi differs from other species in its larger size exceeding two times that of E. fargosomi, which up to now has been thought to be the largest in the genus Encotyllabe. E. latridis differs from other species by the localization of testes and by inconsiderable variations in the length of anchors of opisthaptor. The geographical distribution of the species in question and the problem of their host specificity are delt with in brief.

The widely distributed Dactylogyrus cornu and D. difformis were found to consist of several species. The first species was erroneously believed to include D. distinguendus, D. rutili, D. cornu and D. cornoides sp. n., the second species — D. difformis and D. difformoides. Descriptions and figures of the new species and redescriptions of D. cornu and D. difformis, closely related to them, are given.

The parasite fauna of adult pike from the Penzhina river was found to be much poorer in species (9) than that in pike from the European part of the USSR and West Siberia. The parasite fauna of this year's brood from the Penzhina river is rich (22 species) however. Most of the parasites listed have not been previously recorded either from adults or from young pike in other waters. Some of the listed parasites are normally specific to the minnow, the only member of the Cyprinidae which occur in the Penzhina; other parasitic species were found only in the Cyprinidae or in the Percidae. Two species are new and belong to the genera typical of the Cyprinidae and Cypriniformes. These observation confirm the suggestion of ichthyologists of the existence of an abundant fauna of fishes (Percidae and Cyprinidae) in the basin of the Penzhina in the Upper Tertiary period. Parasites of these fishes are supposed to have left their hosts for the young of pike. In their turn the pike survived the fall of temperature during the glacial period and transgressions of the ocean in the foothill zone of the Paleopenzhina; due to this pike still exist in the basin of the Penzhina river.

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Summary is absent.

Summary is absent.