The A. Aarne-S. Thompson (AaTh) system of classification of folk tales is convenient for distinguishing ielatively stable plot formations characteristic of the late period in the development of national traditions. However, not all the variants of folk tales fit into the AaTh scheme: a part of the existing recorded tales can be fitted into the scheme only conditionally, and hence new subheadings are being introduced into the national catalogues. It is obvious that the accepted international classification does not always fulfil its principal function - the contribution to a comparative study of folk tales of different nations. An investigation of the structure and semantics of Lithuanian folk tales has led us to the conclusio'n that the complex plots which have come down to us are products of a long development and that they have grown into hierarchical systems of elementary plots (hereinafter EP). An elementary plot shows a collision between two personages (or two groups of personages) as a result of which the hero obtains some material or non-material object or is defeated. Because of an uneven development of the plots of narrative folklore and of the tradition in general, there exist, side by side with complex plots, real texts having only one EP. Elementary plots and their constitutent parts, which differ on a concrete level, exhibit semantic similarities, while outwardly similar plots demonstrate semantic differences. This brings us to the second important conclusion: it is essential to establish similarities between texts, not on the basis of external features but on the basis of deep-lying semantic features. We have worked out a special semantic language for the description of EPs and the rules of "translation" (semantic description i made on three levels). Our third conclusion: complex plot structure organises the semantic nucleus of the text – the principal EP (at times there is more than one principal EP, which indicates a combination of folk tales). The plot structure of the text is a network of EPs. We have distinguished three types of logical cause-and-effect relations, an associative, a mechanical relationship, and a detalisation and sum of equal EPs. The most meaningful elements of the plot structure (those which exhibit the most strongly marked 
cause-and-effect relationship, the first type of relationship) form the framework of the tale: its macrostructure. The above conclusions have led us to a radical revision of the concept of the type of the folk tale. Instead of trying to find some ideal model, the folk tale should be viewed from the point of view of its development. Texts which have a simple plot structure, and their variants with a complex plot structure, should both be ctassified as the same type if their semantic nucleus - the principal EP-is monotypal. Having no possibility to dwell on our methodological approach and the levels of description of texts and their elements (a book devoted to these problems is due to come out soon), we shall confine ourselves only to the most important of them which are necessary in determining the type of a folk tale. Here is a simple example illustrating our principles. We shall describe one variant of a popular folk tale "The Kids and the Wolf" (AaTh 123). The plot of the tale is as follows: a she-goat lives in a hut with her kids. Before leaving the hut the she-goat tells her children not to let anyone in. Upon returning the mother calls the kids saying to them: "Open the door; there is hay on my horns". The kids open the door. The wolf overhears the mother's words and when she leaves the hut again, he comes up to the door and addresses the kids with the same words. His voice is low and the kids do not open the door, for their mother's voice is high. The wolf asks a black-srnith to make his tongue thin and then speaks to the kids in the high voice of their mother. The kids open the door and the wolf gobbles them up. The she-goat follows the wolf's trail, finds him asleep, slashes his stomach open, releases her kids, fills the wolf's stomach with stones and stitches it up. On waking up the wolf feels thirsty, goes to the river, bends down to lap water, tumbles into the river and is drowned. The plot of the text consists of three EPs arranged in a linear sequence. The first EP has an unhappy ending ( the wolf gobbles up the kids), the second EP has a happy ending (the she-goat frees the kids), the third EP also has a happy ending (the wolf is no longer dangerous). The hero of the first EP is collective - the kids; the she-goat is a relative of the hero; the wolf is the antagonist, the black-smith is a neutral personage. The internal structure of this EP is quite complex: the same personage performs contradictory actions (the kids do not open the door for the wolf, then open it). This is a feature of convergence of a semantic pair of EPs: the first component of the convergence has lost its end and also its role in the plot structure of the whole text; only a negative outcome of the collision is important for the link with the following EP. The hero of the second and third EPs is the she-goat. Those two EPs share one action - "the she-goat fills the wolf's stomach with stoneC'. In the second EP the she-goat does this to .conceal the fact that the kids have been freed, while in the third EP the stones cause a sense of thirst and heaviness in the wolf. In all the three EPs the hero, a week member of the family, an animal, confronts the antagonist – the wolf, a powerful stranger, a beast. According to the aims of the heroes, all the 
three EPs belong to the class "Striving for freedom from a stranger or from being dominated", the first of the five classes of EPs. We shall limit ourselves to this brief commentary and set aside a fairly long description of the first semantic level. We shall now present the second level of description of each EP. 1. The hero is in a safe place but it is easy to exert influence upon him. A relative of the hero uses the sign of contact and shows his distinctive feature. A relative urges the hero not to establish contact with another personage except him. The antagonist urges the hero to establish contact, using a sign of contact and showing the feature of a stranger. Noticing the feature of a stranger, the hero does not establish contact with the antagonist. The antagonist urges the hero to establish contact using a sign of contact and showing the feature of a relative. The hero establishes contact with a dangerous antagonist taking him for his relative. The hero finds himself inside the antagonist. 2. The hero is deprived of his relative. The hero finds the whereabouts of his relative by the features of the surroundings. The hero takes back from the incapacitated antagonist his relative, leaving in his place an imitation of heaviness in his body. The hero frees his relative. 3. The hero knows that the antagonist is dangerous. The hero makes the antagonist's body heavy and helps to arouse in him a need to get close to a place where he could quench his thirst = a place which is dangerous. The hero finds himself in a place not suitable for life. The third semantic level of the same EPs: 1. The hero is in a dangerous situation. The hero receives information about the sign of contact and about the feature of the hero's relative. The hero is urged not to establish contact with the dangerous antagonist. The hero is urged to establish contact with the dangerous antagonist. The hero does not establish contact with the dangerous antagonist. The hero is urged to establish contact with the dangerous antagonist. The hero establishes contact with the dangerous antagonist. The hero finds himself in the antagonist's power. 
2. The hero loses his- relative. The hero obtains information about the whereabouts of his relative. The hero discovers that his relative is in the place set for him by the antagonist. The hero frees his relative. 3. The hero is in a dangerous situation. The hero places the antagonist in surroundings which are dangerous. The hero renders the antagonist harmless. In the above descriptions of EPs we emphasised the actions determining the outcome of the collision. These are the principal actions (actions of the hero). All concrete EPs are monotypal if their principal actions are interpreted in the same vyay on the third semantic level; differences between the actions on the second level of description make it possible to establish versions of the type of EP, while variations of final situations allow us to establish subtypes of EPs. The name of the principal action is the name of the type of EP, while the results of the EP determine the relationship between elements of a complex plot structure. Below we shall describe the structure and semantics of the text by establishing the types of EPs and relations between them: 1.2.1.6. The hero establishes contact with the dangerous antagonist and finds himself in the power of the antagonist. 1.1.2.1. The hero discovers that his relative is in the place set by the antagonist - the hero frees his relative. 1.1.1.2. The hero places the antagonist in surroundings which are dangerous for his life - the hero renders the antagonist harmless. The most meaningful elements of the plot structure are the first and the second EPs. They make the macrostructure of the text which is described in terms of the results of EPs: The hero finds himself in the power of the antagonist. The hero frees his relative. The first EP governs the second; it is the principal EP. All the animal tales in the structure of whose variants the principal EP belongs to the type 1.2.1.6. will belong to one and the same structural-semantic type. The principal EP of the text under analysis may serve as the basis of an independent work and may also form four more types of simple structures (we are describing their macrostructures): 1. The hero finds himself in the power of the antagonist. 2. The hero finds himself in the power of the antagonist. ~ The hero does not find himself in the power of the antagonist. 3. The hero does not find himself in the power of the antagonist. 
~ The hero finds himself in the power of the antagonist. 4. The hero finds himself in the power of the antagonist. ~The hero frees himself/frees his relative. 5. The hero gets his relative. (The hero frees himself/frees his relative). ~ The hero finds himself in the power of the antagonist. These simple structures are the basis of the theoretically possible versions of this type of folk tale. In the second and third versions the principal EP is joined only by its semantic pairs, in the fourth and fifth versions there can be equivalent EPs having a definite result. Versions based on the linkage of simple structures are also possible. The above structural-semantic type embraces Lithuanian animal folk tales AaTh 57*, 61 B, 123, and also separate variants belonging to AaTh 163, 112*. A similar type can also be found in fairy tales (AaTh 333, 702 B*, individual variants of AaTh 315, 327). In the Lithuanian animal folk tales, the first and the fourth versions are dominant; there are also complex structures (AaTh 61 B). The second and third versions have not yet been found. The material of Lithuanian fairy tales has yielded 106 types of EPs which could become the nucleus of more or less complicated structures; only 58 of them have formed the nucleus, 17 other relict types have isolated variants. The same types can be distinguished in other genres of folk tales too, though the number of types of EPs here is greater. 'The distinguishing of structural-semantic types of folk tales enables us to carry out a more precise comparison of folk tales of different nations, and also of related texts of different genres. This helps solve many problems in folklore studies.