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On the basis of the author's and literary data it was established that fishes of north-eastern Atlantic are parasitized by 89 myxosporidians of 13 families. Of these species the author found 37 of which 17 were described as new ones, 14 were found in new regions and 9 in new hosts. The genera Pseudoalataspora, Neoparvicapsula and Alataspora were first recorded in the region. Myxosporidians from the Celtic sea were studied for the first time. The number of species of myxosporidians occurring in fishes of different genera and families dominate over narrow specific species (51% against 40%). Adaptation of myxosporidians to parasitism in fishes of different biotopes is achieved by means of adaptations of morphological, biological and ecological character. 39% of myxosporidian species occur only in this region. At the same time there is a great similarity with the fauna of the neighbouring regions of Atlantic and nearly complete absence of endemic genera. The fauna of myxosporidians of the Baltic Sea is poor and at the same time heterogenous in its nature, in other regions it is typically marine.

In summer of 1982 studies were undertaken of the physiological age of horse flies in the subzone of southern taiga of the Novgorod region. Anatomical dissection of insects was done on laboratory fixed material. Females of dominant H. bimaculata can complete two gonotrophic cycles at the minimum within a season. Two individuals with traces of three ovipositions were caught. The total duration of flight activity of the species is 55 days. Within the first ten days the population consisted of nulliparous females, by the end of the season 87% of the population was composed by parous females of different age groups. Among horse flies attacking cattle a considerable part belonged to recently parous females. Deviations in the ovaries of tabanids were found to be connected with the process of abortive oogenesis: degeneration of follicles, retained eggs, underdeveloped ovaries, resorption of ovarioles. Spermathecae of all dissected females contained spermatozoids.

Undertaken investigations have shown that the antigen prepared from larvae of O. tarandi is diagnostically effective and stricktly specific only to this infection in the reaction of indirect hemagglutination (RIHA). The experiments have proved the possibility of practical use of RIHA as a principal method of early diagnosis of infection of reindeer caused by О. tarandi.

Fluctuations in the number of eggs in different size groups of females of A. lucii are rather significant. In females 9 mm in length and 4.1 mg in mass potential fecundity is equal on an average to 64 120, in females 20 mm in length and 15.2 mg in mass — to 257 150 eggs, i. e. it increases by a factor of four. At the same time the value of actual fecundity varies by a factor of eleven, i. e. from 11 540 eggs in females which have just started the reproduction to 124 460 eggs in females 20 mm in length. Potential and actual fecundity are in relation to the length of female's body. Three size groups of eggs are considered. During the reproduction period the female of A. lucii is assumed to lay about 600 000 eggs.

The embryonal development of Trichocephalus trichiurus and Eucoleus oesophagicola is described. Clevage of both species is full, bilaterally-symmetrical, determined. At the two blastomere stage the epidermis material is localized in the anterior one. The development of both species lacks the rhomb figure characteristic of nematodes. The mouth opening breaks independent of blastopore. The stylet anlage formation was noted for T. trichiurus.

A comparative study of the formation process of cadaverine in tissues of ascarides, intestine and liver of hen was conducted. Data are given on the activity, pH-optimum of lysine decarboxylase obtained from tissues of helminth and its host. The question on a toxic role of cadaverine during helminthiasis is considered. It has been concluded that the accumulation of cadaverine in the host's intestine can break the permeability of the intestine walls and favour the penetration of toxins of helminths into the host's organism.

The paper contains descriptions, figures and differential diagnoses of tree new species of monocotylids from gills of rays of the South-Chinese and Yellow Seas. Monocotyle undosocirrus sp. n. from Gymnura bimaculata Norm., M. ancylostomae sp. n. from Rhina ancylostoma (Bloch et Schn.) and Merizocotyle sinensis sp. n. from Platyrhina sinensis (Bloch et Schn.) are described. Diagnoses and keys to species of the genera Monocotyle Taschenberg, 1879 and Merizocotyle Gerfontaine, 1894 are given.

No reliable differences were found in the content of general lipids, triglycerides and cholesterol between molluscs of Viviparus viviparus and Limnaea stagnalis infected with parthenites of trematodes and control ones. Certain specific, age and seasonal variability was observed. Reliable sex differences in the cholesterol content were found in V. viviparus infected with parthenites of E. petrowi.

In March of 1982 on Kopetdagh, in the vicinity of the settlement of Jablonevka (1500 m above sea level) on Capra aegagrus there were collected ticks of H. (A.) kopetdaghica represented by 1 nymph, 12 females and 11 males (syn.: H. warburtoni var. kopetdaghicus Kerbabaev, 1962; H. kopetdaghicus Kerbabaev; H. (A.) kopetdaghica Kerbabaev). Earlier these ticks were known from Central Kopetdagh and North Iran.

A description of unknown larva of the species Odagmia exilis is given.

On the basis of the arguments the name С. (С.) setivalva Maslov, 1936 becomes a synonym of С. (С.) fumipennis Stephens, 1825. The characters for distinguishing the adults of C. fumipennis (=C. setivalva) and С. (С.) morsitans Theo. are also discussed. The most reliable feature for distinguishing the female of these species seems to be the presence of the white rings on the IV and V tarsal segments of hind legs in the former species and their absence in the latter one. The male genitalia differ by the ratio of the length of the dististyle to its width in the middle (26—31, mean 27.5, in C. fumipennis and 11—23, mean 16,8, in C. morsitans) as well as by the position of the strong bristles on the basistyle and the number of spines on the apex of the VIII sternite. The synonymy between C. fumipennis and C. sativalva extends the range of C. fumipennis to Bulgaria and the south of the Crimea Peninsula (USSR).

During fixation of fleas infected with plague agent (with preliminary cut heads, limbs and posterior part of the abdomen) in 2.5% glutaric dialdehyde or 2% osmium tetroxide their disinfection was obtained in two days. After double fixation with 2-hour exposure in each of these fixators disinfection of the material was achieved only after additional 2-day maintenance in 70% ethyl alcohol. Fleas, which had been placed into fixators or in 70% ethyl alcohol after double fixation without preliminary dissection, were disinfected completely only in 10 days.

In Lower Priamurje in summer of 1977—1979 Microtus evoronensis was parasitized mainly by fleas of Ceratophyllus calcarifer. Other seven species of fleas recorded from this animal are very rare. They are connected, in general, with other small mammals and birds.

The development of two cestodes, Hymenolepis scutigera and Cucurbilepis skrjabini, from shrews in collembolans of the genus Onychiurus was studied experimentally. Descriptions of larvae at various developmental stages and figures are given. The development of H. scutigera larva till the invagination of cysticercoid carries out for 17 days, that of C. skrjabini larva — for 13 days (at a temperature of 17 to 22°C).

A new species of cercariae from mollusks of Anisus acronicus (Müll) inhabiting tundra water bodies of Chaun lowland (68.5 N. L.) is described. The differential characters of Cercaria tschaunensis are as follows: the size of the body proper is twice as large and the length of the caudal trunk and furcae is 2—3 times less than these in misilar furcocercariae; glands of penetration are of acicular structure; developing furcocercariae are localized in filamentous rediae.

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