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36 species of myxosporideans were found in fishes from 4 lakes and 6 rivers of the Kola Peninsula. The myxosporidean fauna here includes now 38 species. The adaptation of myxosporideans stipulated by complex historic conditions of the formation of the fauna in waters of this region, differences in hydrological regime and severe climate is displayed in the diversity of forms of ecological reconstruction of this group of parasites. A transition of some species to incidental hosts was recorded. Here were found Upper Tertiary (Myxobolus cyprini, M. cyprinicola) and Ponto-Caspian (Myxobolus obesus) species from typical thermophilous fishes which do not occur on the peninsula. According to the relative similarity of their morpho-physiological properties myxosporideans are grouped according to the three of water bodies of the peninsula (lakes, large rivers, small rivers).

It has been established that during experimental infection of chickens with Eimeria tenella the decrease in the activity of lactatdehydrogenase of blood serum and the increase of the activity of glutathionereductase in erythrocytes take place. In birds treated with chemcoccid (70 mg/kg of food) the activity of these ferments does not change. The ferment activity of glucose-6-phosphatdehydrogenase does not change in erythrocytes of sick birds while during the treatment with chemcoccid its activity increases. The activity of aspartate aminotransferase decreases in tissues of muscles and increases in liver and brain of sick birds. The activity of alanine aminotransferase decreases in the brain in three and increases in seven days after the infection.

Nervous system has a similar structure in the two species studied by reconstruction from series of slides and by revealing of cholinesterase. It includes a dumbell-shaped brain, 3 pairs of longitudinal trunks, one ring and two demiring comissures, and a pair of additional ganglia at the bases of tentacles. In addition to ganglia there is one pair of nervous cells in the ring comissure and one pair in the ventral trunks anteriorly to the nervous ring of the sucker. Cells of neurosecretory type are revealed near the brain. The structure of the nervous system proves that Scutariellidae have common origin with the other families of temnocephalids but does not imply a close relationship between Temnocephalida and Udonellida.

Some data concerning infestation of whitefish and vendace with Discocotyle sagittata in Karelian lakes are given. It is demonstrated that dynamics of abundance and structure of parasite population depend on the age composition of the infested fish. Results of helminth frequency distribution in host population are represented.

The paper describes a new genus and five new species of trematodes from fishes of the southern part of the Gulf of Mexico.

On the basis of the authors' and literary data an attempt was made to revise relationships between neoaplectans and other members of the order Rhabditida. Due to the similarity in the structure of the cephalic end, stoma and copulatory organ neoaplectans, strongyloidids and alloionematids are united into the superfamily Alloionematoidea which is transferred into the suborder Cephalobina. Unpaired adanal papilla characteristic of males of alloionematids is regarded as a formation homologous to the supplement.

Ultrafine structure of haemocytes of the ixodid tick Hyalomma asiaticum was studied. On the basis of found transitional forms a scheme of genetic relationships between haemocytes of different types is suggested.

Paired tubular glands of trombiculid mites larvae are situated ventrally and pass from the the anterior wall of the gut forward to the frontal wall of the body where they open with independent efferent ducts. The gland's cells are poorly basophilic and surround the central canal as a rosette. Proximally the basal plasmatic membrane of the gland's cells forms a basal labyrinth with mitochondria and the apical surface with rare microvilli. This suggests that the tubular glands perform the function of aquatic — saline metabolism in feeding larvae, in particular, excrete redundant body fluid consumed during the feeding. Distally the cells of the gland become flattened and lose the basal labyrinth and microvilli. The gland's efferent duct has a thick cuticular membrane. Accumulation of hard excretae in tubular glands was not observed.

5776 voles of the genus Clethrionomys and 110 their nests were examined for the infection with ticks and mites (Parasitiformes) and fleas (Siphonaptera) in West Siberia. 7663 gamasid and close to them mites of 87 species, 5934 ixodid ticks of 6 species and 4738 fleas of 38 species were collected. Abundant and common species are indicated for different landscapes; their abundance, correlation, adaptation to various types of biotopes, community of the faunas of ticks, mites and fleas from different natural zones are analysed.

A study was carried out of ultrastructure of malpighian tubules of 4 species of fleas as follows: Xenopsylla cheopis, Ceratophyllus fasciatus, Leptopsylla segnis, Ctenophthalmus orientalis. All cells of malpighian tubules are of polar structure: their apical department is represented with microvilli while basal one — with a system of membrane invaginations forming the basal labyrinth. The most developed system of basal invaginations is observed in distal cells of the malpighian tubules. Microvilli of the apical surface of the cells do not contain mitochondria, the latter are localized mainly in supranuclear and basal parts of the cell. In cells and cavity of the central and proximal parts of the malpighian tubules there are sphere crystals. Malpighian tubules of fleas have no distinct morphological departments though ultrastructure of the cells in different parts of the tubules is not identical.

Some new features for distinguishing the 4th stage larvae of Culiseta (Culicella) morsitans Theo. and С. (C.) ochroptera Peus are given because their differentiation according to the number of branches of upper frontal hairs (5-C) is not sufficiently reliable. A mean branching of these hairs in C. morsitans larvae decreases clinally in the direction from north to south in the range of the species in the USSR extending to the east up to Khabarovsk region (Soviet Far East). The opinion of Wood et al. (1979) is supported that there are no sufficient arguments to consider C. morsitans from Palearctic and Nearctic regions as two subspecies, C. m. morsitans Theo. and C. m. dyari Coq., therefore the name C. m. dyari Coquillett, 1902 should be regarded as a synonym of C. morsitans Theobald, 1901.

The mollusk Mactra chinensis Philippi, 1846 (Syn.: M. sulcataria Deshayes, 1853) in the Possjet Bay (Sea of Japan) was found to be infected by 87 per cent with the earlier unknown progenetic metacercaria of Decemtestis. The larva has a fully developed reproductive system, its cysts are localized in the distal parts of the siphones of the host. Some ecological aspects for this species have been studied. The life cycle of the parasite is to be investigated.

Instead of Canada balsam epoxy resin ED-6 was used for making constant preparations of trematodes and cestodes. The preparations manufactured in this way do not require a long time for drying and so can be used more readily for studies.

In autumn of 1981 Sigara concinna was first recognized as an intermediate host of Tatria biremis from the lake Sorbulak (south-eastern Kazakhstan). 37 larvae of T. biremis were found in the abdominal cavity of infected S. concinna (0.15%). The description of cysticercoid is given. In Podiceps caspicus (16 specimens of 20 examined) and P. cristatus (one specimens of two examined) there were found cestodes of C. biremis.

Protoclepsis tessulata (Müller) was recovered from nestlings of common gall (Larus canus L.), black-headed gull (L. ridibundus L.) and common turn (Sterna hirundo L.) in one of lakes of Central Yakutia. The infection rate of nestlings with adult leaches is not high. Heavy pathology or mortality of birds was not observed. The infection of nestlings occur in coastal thickets of reed and sedge where they hide from danger.

Summary is absent.

Summary is absent.

Summary is absent.

Summary is absent.