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The partial revision of the generally accepted classification of the morfological forms of trypanosomatid flagellates (Hoare, Wallace, 1966) is proposed. Only "flagellar" characteristics without evaluation of the form of the body and sistematic position of the flagellates are used in the new variant of the classification. Six basic morfological forms of trypanosomatids have been included in proposed scheme: amastigotes, endomastigotes, promastigotes, opisthomastigotes, epimastigotes, trypomastigotes.

The new cestode species is described from the intestine of the crab eater seal Lobodon carcinophagus living in pacific region of Antarctic. It differs from other diphyllobothriids by clear wavy lateral margins of the body. It is close to D. scoticum by the presence of uterine sack, but it has larger size of the body, lesser craspedotity of segments, lesser size of scolex, longer neck, thiner tegument, 3 times thicker layers of longitudinal and transversal muscles, 2 times greater number of testicles (per transversal section of the segments), another form and position of the bursa of cirrus and of the testicular vesicle, larger uterine sack consisting about one third of the total uterine volume.

Serial transsections of the oncosphere T. nodulosus were investigated by means of the transmissive electron microscopy. The cytological characteristic has been given for cell types as follows: feebly differentiated, muscular, neural, tegumental cells, single cells of penetration, and cells of excretory system. The processes of tegumental cell are provided with microtubules, go through the basal plate, and form mace-like expansions. Subsequently they form the external cytoplasm of procercoid's tegument. The muscular cells include the somatic cells and cells connected with hook apparatus. The nerval cells are located in central part of oncosphere, and their processes are aglomerated in posterior one third of oncosphere and innervate the system of hooks and the associated muscles. Few feebly differentiated cells are concentrated in the central part of oncosphere. The excretory system consist of two cirtocytes and excretory channels, which are subdivided into three parts connected one to another by cell contacts alike desmosomes. Proximal parts surround the ciliary flame of the cirtocyte, the distal part is ended in ciliary shell by the excretory pore.

The study of the morphogenesis of haptor's structures of Diclybothrium armatum from Acipenseridae has shown that hooks of second-fifth pairs are not transformed into clamp sclerites as it was suggested earlier, but disappear. These hooks are substituted by the clamp sclerites developed by an independent way.

The content of sodium, potassium, calcium and magnesium ions was determined in cestodes Ligula intestinalis, Eubothrium rugosum, and Triaenophorus nodulosus. In freshwater fishes the total concentration of Na, K, Ca, Mg ions in cestode tissue water is practically similar to that of fishes muscles and in serum. It was suggested that examined cestodes have isoosmotic regulation of the water-salt balance.

The possibility to awake the disseminated infection of Leishmania infantum in golden hamsters Mesocricetus auratus, hispid cotton rats Sigmodon hispidus, soft furred rats Mastomys natalensis by means of different immunodepressants has been examined. On the background of the immunosupression caused by corticosteroids of short time activity (metipred, hydrocortison) leishmaniae were revealed both in the target organs (spleen, liver, marrow) and in lungs, in cases of using the corticosteroid of prolonged activity (tricort-40) leishmaniae were observed also in lungs, kidneys, testis.

The new method of isolation and purification of presporogonial stages; young and mature spores of microsporidia Nosema grylli, a parasite of the criket fat body has been evaluated. The proposed method includes the consequence of following operations: (1) fat body preparation: (2) homogenizing of fat body in glass homogenizer with teflon pestle: (3) filtration through cotton wad and filter paper: (4) first centrifugation in phosphate buffered solution: (5) second centrifugation of the chosen zone contents in Percoll density gradient and (6) washing of the isolated fraction. The first centrifugation divides the sediment to the following zones: the upper layer consists of merogony and early sporogony stages, slight amount of host cell nuclei and small vesicles; the intermediate layer consists of young spores, nuclei and host cell cytoplasmic debris; the lowest layer consists of pure mature spores. After centrifuging in Percoll gradient the merogony and early sporogony stages stop in the zone with Percoll density 1.016 g/ml. Mature spores sediment on the very bottom of centrifuging tube: young immature spores are distributed through the whole tube from 1.016 g/ml up to the bottom in correspondence with their maturing grade. All purification steps take approximately 1 hour, are simple enough and may become the routine procedure while biochemical studies on microsporidia.

The infection rate with monogeneans of different sites of fish gills was examined. The comparative analysis of average parts (in %) was made after Fisher Fd= (φ1— φ2)2 [(n1n2) / ( n1+n2)], (v1= 1, v2 = n1+n2 — 2), where φ is a percentage in radians, n — the number of fishes dissected, v — degrees of freedom. It was shown statistically, that part (%) of dactylogyrids on II pairs of the gills is significantly greater than parts from I and III pairs of the gills. The parts of the parasites were not distinguished on I and III pairs of the gills. The part of worms on IV pair of the gills is the least. It was shown that statistically significant part of the dactylogyrids was observed in the middle sector of the gills. Factors, which could leed to unequal distribution of monogeneans on the gills, are discussed. The main factor appears to be a volume of water stream passing through different pairs of the gills.

In 70 natural populations and laboratory strains of Culex pipiens from the former Soviet Union (32 settlements, 37 — 62°N, 38 — 93°E) the larval siphonal index was studied, in 29 populations the adult biological peculiarities (the autogeny, the stenogamy and the bloodsucking activity on the human) were studied also in the laboratory. The individual siphonal index varies considerably from 2.2 to 7.9 and has the normal distribution shape. The mean index is correlated with the larval biotope (open or underground reservoirs) and with biological peculiarities. In autogenous and stenogamous populations the mean siphonal index varies from 3.7 to 4.6 (average 4.1), in nonautogenous and eurigamous ones — from 4.7 to 5.6 (average 5.1). The biological mechanisms which provide the differentiation and isolation of the forms C. p. pipiens and C. p. molestus in the temperate zone are discussed. These mechanisms include the capacity to diapause, the ability to copulate in the restricted space (stenogamy), and the biotopic specialization of the larvae (open or underground reservoirs). The individual variation of siphonal index is often too high, therefore the identification of the individual larvae is unreliable. However, the mean siphonal index of the population can be recommended for the identification of the forms in populations from the temperate latitudes: in C. p. molestus the mean siphonal index is 4.3 and lower, in C. p. pipiens it is 4.8 and higher, the rare populations with the intermediate indexes require the additional biological study.

Transformations of shape of the ghathosoma was studied for all ontogenetic phases in 4 tick species of Ixodes s. str. by means of new methods of "geometrical morphometries". The gnathosoma shape is shown to be nearly constant among larvae, nymphae and mature females, but its size varies quite considerably between nymphae and females. Contrary to this, transition from nymphae to mature males involves drastic transformations of the shape, while size of the gnathosoma remains unchangeable. Gnathosoma shape transformations among larvae and females can be considered as a progression of the same morphological type realized already at larval level. Gnathosoma size enlargement in this progression is associated with greater ability to consume huge amount of the host blood. Ontogenetic variation of the gnathosoma shape is most canalized in I. persulcatus. Shape of gnathosoma is quite similar in all species under consideration, so its transformations among species are minute and not canalized. The data reported herewith confirm more similarity between I. ricinus and I. persulcatus, from one side, and between I. laguri and I. redikorzevi, from another side, save that females of the latter species is placed in intermediate position between these two groups. Such a similarity pattern in gnathosoma shape is most probably explained not by genealogical relationships of the species, but by similarity of parasitism types. Certain differences between species by amplitude of gnathosoma shape transformations also correspond to their ecological peculiarities.

Three new species of the feather mite genus Bychovskiata Dubinin, 1951 (Avenzoariinae) are described from plover-like shorebirds: Bychovskiata bisulcata sp. n. from the Pied Oyster-catcher Haematopus ostralegus (Haematopodidae), B. perforata sp. n. from the Red-kneed Dotterel Erythrogonys cinctus (Charadriidae), and B. bidentata sp. n. from the Hooded Dotterel Charadrius rubricollis (Charadriidae). Differential diagnoses are provided for the described species.

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Summary is absent.