The present invention relates to a composition in the foam form comprising a continuous oily phase. The compositions according to the invention can be compositions for making up or caring for keratinous substances, in particular the skin, lips, eyelashes, eyebrows or nails. The coraposltion may or may not be coloured. Each composition can be a foundation, a face powder, an eye shadow, a concealer, a blusher, a lipstick, a lip balm, a lip gloss, a mascara, an eyeliner or a product for making up the body or colouring the skin. The care cowposition can be a product for caring for the eyelashes, lips or skin of the body and face, in particular an antisun product. Compositions in the foam form which are oil-in-water or wax-in-water emulsions comprising a continuous aqueous phase are known. However, these compositions do not always exhibit the gloss desired by consumers, in particular in the case of lipsticks. The document US 2006/147390 also teaches compositions comprising oils, waxes and a gas in a minimum amount of 20%. However, waxes alone do not make it possible to obtain a foam texture which is satisfactory and which exhibits an improved gloss. A search is thus underway to obtain compositions which exhibit a normal texture, in the foam form, and which exhibit a satisfactory gloss, via the incorporation of a certain amount of oils which make it possible to contribute these gloss properties. A search is also underway to formulate compositions comprising a high content of volatile or nonvolatile oils or organic solvents, BO as to improve the hold and/or the resistance to water or to sebum and/or the transfer-free properties of the said compositions. In addition, the compositions in the foam form must exhibit good stability ©v»r time, in particular in terms of homogeneity and appearance of the product. it is an aim of the present invention to provide another formulation route for a composition for coating keratinous substances which exhibits a foam texture. More specifically, a aubjset-matter of the invention is a cosmetic composition in the foam form comprising a continuous oily phase and at least one structuring agent for the oily phase, the said composition being devoid of wax. The term "composition in the foam form" is understood to mean a composition comprising a gas phase (for example air) in the form of bubbles; another term is "composition expanded in volume". The composition in the foam form exhibits a light texture and is easy to withdraw and to spread over keratinous substances. Another subject-matter of the invention is a method for coating keratinous substances, comprising the application, to the said keratinous substances, of at least one layer of at least one cosmetic composition in the foam form comprising a continuous oily phase and at least one structuring agent for the oily phase, the said composition being devoid of wax. The method for coating keratinous substances according to the invention consists in applying the composition in the foam form to keratinous substances; it differs from the processes of the prior art in that the foam ia not formed in situ on the keratinous substances, that is to say that the foam is not created after application of the said composition. In particular, a delayed-expansion composition, which is a system in which a "volatile" agent is released or formed in the composition after the latter has been applied to the keratinous substances, is not involved. Specifically, delayed-expansion compositions are created after exposure of a gel to atmospheric pressure and/or to shearing and/or to a tespsrature greater than ambient temperature. Another subject-matter of the invention is a kit for making up and/or for a nontherapeutic care of keratinous substances, comprising: a composition in the foam form comprising a continuous oily phase and at least one structuring agent for the oily phase, the said composition being devoid of wax, and an applicator comprising at least one application component configured in order to apply the composition to the keratinous substances. Density The composition in the foam form exhibits in particular a density l&&m») of less than or equal to 0.95, preferably of less than or equal to 0.9, better still of less than or equal to 0.8. The density is preferably greater than or equal to 0.2 and better still greater than or equal to 0.3. The density is measured according to the following protocol: a container, the volume Vo (cm3) of which is known with an accuracy of ± 0.005 cm3 (Vo being of the order of 10 cm5) , is weighed by means of a precision balance to ± 0.00005 g. Its weight is recorded as wo (g) . This container is carefully filled with the foam until the container overflows. The surface of the container is then levelled with a straight blade in order to obtain a perfectly flat foam surface. The weight w 9. Examples of Rx groups are thoee derived from fatty acids chosen from the group consisting of acetic acid, propionic acid, butyric acid, caproic acid, caprylic acid, pelargonic acid, capric acid, undecanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, isostearic acid, arachidic acid, behenic acid, oleic acid, linolenic acid, linoleic acid, eleostearic acid, arachidonic acid, erucic acid and their mixtures. Examples of esters are, for example, Purcellin oil (cetostearyl octanoate), isononyl isononanoate, iaopropyl mystristate, 2-ethylhaxyl palmitate, 2-octyl-dodecyl atearate, 2-octyldodecyl arucate, isostearyl isostearate and heptanoatas, octanoates, decanoates or ricinoleates of alcohols or of polyalcohols, for example of fatty alcohol*. Advantageously, the eaters are chosen from the compounds of the above formula (I J in which Rt represents an unaubstituted linear or branched alkyl group optionally comprising one or more ethylenic double bonds and of 1 to 40 carbon atoms, preferably of 7 to 19 carbon atoms, and Ra represents an unaubstituted linear or branched alkyl group optionally comprising one or more ethylenic double bonds and of 1 to 40 carbon atoms, preferably of 3 to 30 carbons and better still of 3 to 20 carbon atoms. Preferably, Ri is an unawbetitubed branched alkyl group of 4 to 14 cartoon atoms, preferably of 8 to 10 carbon atoms, and R2 is an unaubatituted branched alkyl group of S to 15 carbon atoms, preferably of 9 to 11 carbon atoms. Preferably, in the formula (I), Ri-CO- and Rs have the same number of carbon atoms and derive from the same radical, preferably an unsubetituted branched alkyl radical, for example the isononyl radical, that is to say that, advantageously, the ester oil molecule is symmetrical. The ester oil will preferably be chosen from the following compounds: isononyl isononanoate, cetostearyl octanoate, iaopropyl myristate, 2-ethylhaxyl palmitate, 2-octyldodecyl stearate, 2-octyldodecyl erucate. isosteryl isoatearate The oily phase can comprise from 0.5 to 100% by weight, in particular from 1 to 80% by weight, especially from 5 2 to 3 0% by weight and more particularly from 2 to 40% by weight of eater oil or oils. > The structuring agent for the oily phase is advantageously chosen from polymeric structuring agents. The term "polymer" is understood to mean, within the meaning of the invention, a compound having at least 2 repeat units, preferably at least 3 repeat unite and better still 10 repeat units. The polytneric structuring agent advantageously exhibits a weight-average molecular weight of greater than or equal to 4000, better still of greater than or equal to 5000 and even better still of greater than or equal to 6 000 which can range up to 500 000. The polymeric structuring agents can in particular be chosen from: A} silicone polymers comprising at least one unit comprising: 1) polyorganosiloxanee comprising at least two groups capable of establishing hydrogen interactions, these two groups being situated in the chain of the polymer, and/or 2) polyorgonosiloxanes comprising at least two groups capable of establishing hydrogen interactions, these two groups being situated on grafts or branchings, the said groups capable of establishing hydrogen interactions being chosen from ester, amide, sulphonamide, carbamate, thiocarbamate, urea, urethane, thiourea, oxamido, guanidino and biguanidino groups and their combinations, B) polyaaide polymers comprising a polymeric backbone having hydrocarbon repeat units provided with at least one nonpendent amide unit and at least one optionally functionalized pendent fatty chain and/or at least one optionally functionalred end fatty chain which comprise at least 4 carbon atoms and which are bonded to these hydrocarbon units, C) olefin copolymers, D) partially or completely crosslinked organopolysiloxane elastomers of three-dimensional structure, B5 semicryetalline polymers, F) esters of dextrin and of fatty acid, and their blends. The structuring agent or agents can represent from 0.1 to 60% by weight, with respect to the total weight of the composition, preferably from 0.5 to 50% by weight and more preferably still from 1 to 40% by weight. The amount off oily phase structuring agent can be adjusted by a person skilled in the art according to the structuring properties of the said agents. A) Silicon* polymers The silicone polymers of the composition are preferably aolid at ambient temperature (25°C) and atmospheric pressure (760 ramHg). The term "polymer" is understood to mean, within the meaning of the invention, a compound having at least 2 repeat units, preferably at least 3 repeat units and better still 10 repeat units. The silicone polymers used as structuring agents in the composition of the invention are polymers of the polyorgaaoeiloxane type, such as, for example, those described in the documents US-A-5 874 069, US-A-5 919 441, 0S-A-6 051 216 and US-A-5 981 660. According to the invention, the polymers used as structuring agent can belong to the following two families j 1) polyorganoailoxaaes comprising at least two groups capable of establishing hydrogen interactions, these two groups being situated in the chain of the polymer, and/or 2) polyorganosiloxawwi comprising at least two groups capable of establishing hydrogen interactions, these two groups being situated on grafts or branchings. The groups capable of establishing hydrogen interactions can be choson from ester, amide, sulphonamide, carbamate, thiocarbaraate, urea, urathane, thiourea, oxamido, guanidino and biguanidino groups and their combinations. a) According to a first alternative form, the silicone polymers are polyorganoeiloxanea as defined above, the groups capable of establishing hydrogen interactions of which are positioned in the chain of the polymer. The silicone polymers can more particularly be polymerB comprising, at least one unit corresponding to the general formula (I): (Formula Removed) in which: 1) R4, R5, R6 and R7, which are identical or different, represent a group cho»en from: saturated or unsaturated and linear, branched or cyclic C1 to C40 hydrocarbon groups which can comprise, in their chain, one or more oxygen, sulphur and/or nitrogen atoms aad which can be substituted, partially or completely, by fluorine atoms, C6 to C10 aryl groups optionally substituted by one or more C1 to C4, alkyl groups, - polyorganosiloxane chains comprising or not comprising one or wore oxygen, sulphur and/or nitrogen atoms, 2) the X groups, which are identical or different, represent a linear or branched C1 to C30 alkylenediyl group which can comprise, in its chain, one or more oxygen and/or nitrogen atoms, 3)Y is a C1 to C50 alJcylene (linear or branched) , arylene, cycloalkylene, alkylarylene or arylalkylene divalent group, saturated or unsaturated, which can comprise one or more oxygen, sulphur and/or nitrogen atoms and/or carry, as substituent, one of the following atoms or groups of atoms: fluorine, hydroxyl, C3 to Cg cycloalkyl, Ci to C«0 alkyl, C$ to C10 aryl, phenyl optionally substituted by 1 to 3 groups of the type cx to C3 alkyl, Ci to Cj hydroxyalkyl and Ca to C6 aminoalkyl, or 4) Y represents a group corresponding to the formula: in which: - T represents a saturated or unsaturated and linear or branched trivalent or tetravalent C3, to C24 hydrocarbon group which is optionally substituted by a polyorganosiloxane chain and which can comprise one or more atoms chosen from 0, N and S, or T represents a trivalent atom chosen from N, P and Al, and R8 represents a linear or branched C1 to C50 alkyl group or a polyorganosiloxane chain, which can comprise one or more ester, amide, urethane, thiocarbamate, urea, thiourea and/or sulphonamide groups, which way or reay not be bonded to another chain of the polymer, 5) the 0 groups, which are identical or different, represent divalent groups chosen from: (Formula Removed) where R9 represents a hydrogen atom or a linear or branched C1 to C20 alkyl group, provided that at least 50% of the R5 groups of the polymer represent a hydrogen atom and that at least two of the G groups of the polymer are a group other than: and (Formula Removed) 6) n is an integer ranging from 2 to 500, preferably from 2 to 200, and m ia an integer ranging from 1 to 1000, preferably from 1 to 700 and better still from 6 to 200. According to the invention, 80% of the K*, Rs, R* and R7 groups of the polywer are preferably chosen from methyl, ethyl, phenyl and 3,3,3-trifluoropropyl group*. According to the invention Y can represent various divalent groups, furthermore optionally comprising one or two free valences in order to establish bonds with other units of the polymer or copolymer. Preferably, Y represents a group chosen froms a) linear C1 to C20. preferably C1 to C10, alkylene groups, b) branched C30 to C56 alkylene groups which can comprise rings and nonconjugated unsaturations, c) Cs-c6 cycloalfcylene groups, d) phenylene groups optionally substituted by one or more C1, to C40 alkyl groupa, e) C1 to C20 alkylene groups comprising from 1 to 5 amide groups, f) C1, to C20 alkyless groups coaprising one or more substituenta chosen from nydroxyl, C3 to C8 cycloalkane, Cx to C3 hydroacyalkyl and C1 to C6 alkylamine groups, g) polyorganosiloxane chains of formula: (Formula Removed) in which R4, R9, R*, R7, T and m are as defined above, and h) polyorgaaaosiloxane chains of formula: (Formula Removed) b) According to the second alternative form, the polyorganosiloxanes can be polymers comprising at least one unit corresponding to the formula (II): (Formula Removed) in which: - R* and ft*, which art identical or different, are as defined above for the formula (I), R10 represents a group as defined above for R* and R*, or represents the group of formula -X-G-R" in which X and G are as defined above for the formula (I) and Rxa represents a hy#c©gen atom or a saturated or unsaturated and linear, branched or cyclic Ci to C50 hydrocarbon group which optionally comprises, in its chain, one or more atoms chosen from 0, S and N and which is optionally substituted by one or more fluorine atoms and/or one or more hydroxy1 groups, or a phenyl group optionally substituted by one or more Cj, to C4 alkyl groups, R11 represents the group of formula -X-G-R12 in which x, G and R" are as defined above, - mi is an integer ranging from 1 to 998, and - m2 is an integer ranging from 2 to 500. According to the invention, the polymer used as structuring agent can be a homopolymer, that is to say a polymer comprising several identical units, in particular units of formula (I) or of formula (II). According to the invention, use may also be made of a polymer composed of a copolymer comprising several different units of formula (I) , that is to say a polymer in which at least one of the values R*, Rs, R*, R7, X, G, Y, m and n is different in one of the units. The copolymer can also be formed from several units of formula (II) in which at least one of the values R4, Rg, R10, Ru, mi and n»a is different in at least one of the units. Use may also be made of a polymer comprising at least one unit of formula (I) and at least one unit of formula (II), it being possible for the units of formula (I) and the units of formula (II) to be identical to or different from one another. According to an alternative form of the invention, use may also be made of a polymer additionally comprising at least one kydrocarboa unit comprising two groups capable of establishing hydrogen interactions chosen from ester, amide, sulphonamide, carbamate, thiocarbamate, urea, urethane, thiourea, oxamido, guanidino and biguanidino groups and their combinations. These polymers can be block polymers or grafted polymers. According to an advantageous embodiment of the invention, the groups capable of establishing hydrogen interactions are amide groups of formulae -C(0)NH- and -HN-C(O)-. In this case, the structuring agent can be a polymer comprising at least one unit of formula (III) or (IV): (Formula Removed) in which R*, R5, R*, R7, X, Y, m and n are as defined above. Such a unit can be obtained: either by a condensation reaction between a silicone comprising a, to-carboxylic acid ends and one or more diamines, according to the following reaction scheme: (Formula Removed) or by reaction of two molecules of a-unaaturated carboxylic acid with a diamine, according co the following reaction scheme: (Formula Removed) followed by the addition of a siloxane to the ethylenic (Formula Removed) in which X1-(CHa)a- corraaponde to the X defined above and I, R\ RS, R*, RT and m are as defined above, - or by reaction of a silicone comprising ar The term "hydrocarbon repeat units" is understood to mean, within the meaning of the invention, a unit comprising from 2 to $0 carbon atoms and preferably from 2 to 60 carbon atosts, carrying hydrogen atoms and ! optionally oxygen atoms, which can be saturated or unsaturated and linear, branched or cyclic. These unite each additionally comprise at least one amide group which is advantageously nonpendent and which occurs in the polymeric backbone. Advantageously, the paajteat chains are directly bonded to at least one of the nitrogen atoms of the polymeric backbone. The polyamide can comprise, between the hydrocarbon units, silicone units or oxyalkylene units. in addition, the polyawida of the composition of the invention advantageously oowprisea from 40 to 98% of fatty chains, with respect to the total number of the amide units and fatty otoains and better still from 50 to 95%. Preferably, the pendent fatty chains are bonded to at least one of the nitrogen atoms of the amide units of the polymer. in particular, the fatty chains of this polyamid* represent from 40 to 984 of the total number of the amide units and of the fatty chains and better still from 50 to 95%. Advantageously, the polyemide exhibits a weight-average molecular weight of leas than 100 000 (in particular ranging from 1000 to 100 000) , especially of leas than 50 000 (in particular ranging from 1000 to 500 000) and more particularly ranging from 1000 to 300 000, preferably from 2000 to 20 000 and better still from 2000 to 10 000. The polyaraide is in»olul»le in water, in particular at 25°C. It especially does not comprise an ionic group. Mention may be made, as preferred polyaniides whioh can be used in the invention, of pe-lyamldes branched by pendent fatty chain* and/or end fatty chains having from 6 to 120 carbon atoms and better still from 8 to 12 0 carbon atoms and in particular from 12 to 68 carbon atoms, each end fatty chain being bonded to the polyamide backbone via at least one bonding group. The bonding group can be chosen from ester, ether, amine, urea, urethane, thioee%er, thioether, thiourea and thiourethane groups. Preferably, these polymers comprise a fatty chain at each end of the polyaraide backbone. These polymers are preferably polymers resulting from a polycondensation between a dicarboxylic acid having at least 32 carbon atoms (having in particular from 32 to 44 carbon atoms) and an amine chosen from diamines having at least 2 carbon atoms (in particular from 2 to 36 carbon atoms) and triawines having at least two carbon atoms (in particular from 2 to 36 carbon atoraa). The diacid is preferably • diwer resulting from a fatty acid coapriting ethylene unsaturation having at least 16 carbon atoms, preferably from 16 to 24 carbon atomB, such aa oleic acid, linolaic acid or linolenic acid. The diamine is preferably ethylenedi amine, hexylenediamine or hexamethyleaediamine. The triamine is, for example, ethyleastriasiine. For the polymers comprising one or two and carboxylic acid groups, it i9 advantageous to esterify thetn with the monoalcohol having at least 4 carbarn atom, preferably from 10 to 36 carbon atows and better still from 12 to 24 carbon atoms and even better still from 16 to 24 carbon atoms, for example IS carbon atom*■ The polyamide of the composition according to the invention can be chosen in particular from polymers of following formula (A) : (Formula Removed) in which: n is an integer ranging from 1 to 30, - R'i independently represents, in each case, a fatty chain and ia chosen from an alkyl or alkenyl group having at least one carbon atom and in particular from 4 to 24 carbon atoms; - R'2 independently represents, in each case, a hydrocarbon radical coeprising from l to 52 carbon atoms; - R'3 independently represents, in each case, an organic group comprising at least one atom chosen from carbon, hydrogen or nitrogen atonus, provided that R'3 comprises at least 3 carbon atoms; - R'< independently represents, in each case: a hydrogen atom, en alkyl group comprising from l to 10 carbon stems or a direct bond to at least one group chosen from R'j and another R'4, so that, when the said group is another R'4, the nitrogen atom to which both R'3 and R'4 are bonded forms part of a heterocyclic structure defined by R'4-H-R'j, provided that at least 50% of the R'4 groups represent a hydrogen atom, and L represents a bonding group as defined above in the description, optionally substituted by at least one R*i group as defined above. -C—O— According to one embodiment, these polymers are chosen from polymers of formula (A) in which the bonding group L represents an ester group o These polymers are more especially those described in the document OS-A-5 783 657 of Ohion Camp. Bach of these polymers satisfies in particular the following formula (B) : (Formula Removed) in which: m denotes an integral number of amide units such that the number of ester groups represents from 10% to 501 of the total number of the ester and amide groups; R1 is in each case independently an alkyl or alkenyl group having at least 4 carbon atoms and in particular from 4 to 24 carbon atoms; R3 independently represents, in each case, a C4 to C42 hydrocarbon group, provided that 50% of the R2 groups represent a C30 to C4S hydrocarbon group ,- R3 independently represents, in each case, an organic group provided with at least two carbon atoms, with hydrogen atone and optionally with one or more oxygen or nitrogen atoms; and R4 independently represent a, in each case, a hydrogen atom, a C% to do alkyl group or a direct bond to R3 or to another R4, so that the nitrogen atom to which both Rj and R4 are bonded forme part of a heterocyclic structure defined by R4-N-R3, with at least 50% of the R4 groups representing a hydrogen atom. In the specific case of the formula (B), the optionally functionalised end fatty chains within the meaning of the invention are end chains banded to the final nitrogen atom of the polyamide backbone. In particular, the ester groups of the formula (B), which form part of the end and/or pendent fatty chains within the meaning of the invention, represent from 15 to 4 0% of the total number of ester and amide groups and better still from 20 to 35%. Furthermore, m advantageously represents an integer ranging from 1 to S and better still of greater than 2. Preferably, R1 is a C13 to C« and preferably d« to d2 alkyl group. Advantageously, Ra can be a C16 to C42 hydrocarbon (alkylane) group. Preferably, at least 50% and better still at least 75% of the R3 groups are groups having from 30 to 42 carbon atoms. The other R2 groups are hydrogenated d to C19 and even C, to C12 groups. Preferably, R3 represente a C2 to C36 hydrocarbon group or a polyoxyalkylena group and R, represents a hydrogen atom. Preferably, R3 represents a C, to da hydrocarbon group. The hydrocarbon groups can be saturated or unsaturated and linear, cyclic or branched groups. Furthermore, the alkyl and alkylene groups can be saturated or unsaturated and linear or branched groups. Generally, the polymers of formula (B) are provided in the form of blends of polymers, it being possible for these blends to additionally comprise a synthetic product corresponding to a compound of formula (B) where m has the value of 0, that is to say a diester. Mention may be made, as example of polyamides of formula (B) which can be used in the composition according to the invention, of the commercial products sold by Arizona Chemical under the name8 Uniclear 80 and Uniclear 100 VG, which are sold respectively in the form of an 80% (as active material) gel in a mineral oil and at 100% {as active material) . They have a softening point from 88C to 94°C. These commercial products are a blend of copolymers of a C36 diacid condensed with ethyleaeiaiamine, with a weight-average molecular weight of approximately 6000. The end ester groups result from the •aterifieatioxt of the remaining acid endings with cetyl alcohol, stearyl alcohol or their mixtures (also known as cetearyl alcohol). Mention may also be made, as polyamides corresponding to the general formula (A) , of polymers comprising at least one end fatty chain bonded to the polymeric backbone via at least one tertiary amide bonding group (also known as amide terminated polyamide or ATPA). Such polymers are available, for example, under the reference Sylvaclear A 2SO0 V from Arizona Chemical. For further information on these polymers, reference may be made to the document US 6 503 522. According to one embodiment, the polyamide of formula (A) can also comprise at lea*t one end fatty chain bonded to the polyiwric backbone via at least one ether or polyather bondiag group (it is then said to be an ether terminated poly(#tber)amide). Such polymers are described, for example, in the document OS 6 399 713. Mention way also be made, as polyamide which can be uaed in the invention, of polywaide resins resulting from the condensation of an aliphatic dicarboxylic acid and of a diamine (including the confounds having more than 2 carbonyl groups and 2 amine groups), the carbonyl and amine groups of adjacent whole units being condensed via an amide bond. These polyamide resins are in particular those sold under the Versaraid* trade mark by General Mills Inc. and Henkel Corp. (Versaraid 930, 744 or 1655} or under the Oneroid" trade mark, in particular Onamid S or C, by Olin Mathieson Chemical Corp. These resins have a weight-average molecular weight ranging from 6000 to 9000. For further information on these polywaides, reference may be made to the documents US 3 €45 705 and US 3 148 125. More especially, Versamid* 930 or 744 is used. It is also possible to use a poly (ester amide) comprising ester ends (ester-terminated poly(ester amide) or BTPEA), such as, for example, those whose preparation is described in the document US 6 552 160. This polyamide is, for example, Sylvaclear C 75 V from Arizona Chemical. It is also possible to use the polyamides sold by Arizona Chemical under the Uni-Res references (2658. 2931, 2970, 2621, 2613, 2624, 2665, 1554, 2623, 2662) and the product sold under the reference Macromelt 6212 by Henkel. Such polymers are described, for example, in the document US 5 500 209. It is also possible to use polyamide resins resulting from vegetables, such as those described in Patets US 5 783 6S7 and OS 5 ftfl 570. The polyatnida advantageously has a softening point of greater than 65°C which can range up to 190°C. 5 Preferably, it ekhibite a softening point ranging from 70 to 130"C and better still from 80 to 105°C. The polyamide is in particular a nonwaxy polymer. Preferably, the polyamide corresponds to the formula 0 (B) mentioned above. C) olefin capolyear The composition accordinf to the invention conprises at 5 least one olefin copolymer preferably chosen from amorphous olefin copolymers. The term "olefin copolymer" is understood to mean, within the weaning of the present patent application, 3 any copolymer formed by polymerization of at least one olefin and of another additional monomer other than the said olefin. The olefin can in particular be a monomer comprising ethylenic uneaturation. Mention may be made, as example of olefin, of ethylenic hydrocarbon monomers having in particular one or two ethylenic unsaturatione and having from 2 to 5 carbon atoms, such as ethylene, propylene, butadiene or isoprene. The terra "amorphous polywtr* is understood to mean a polymer which does not have a crystalline form. This polymer can also be a film-form!sag polymer, that is to say that it is capable of forming a film when it is applied to the skin. The olefin copolymer can in particular be a diblock, triblock, raultiblock, radial or star copolymer or their blends. Such compounds are described, for example, in Application US-A-2002/005562 and In Patent US-A-5 221 534. An amorphous block copolymer of atyrene and of olefin is advantageously chosen. The block copolymer is preferably hydrogenated in order to reduce the residual ethylenic unaaturations after the polymerisation of the monomers. In particular, the hydrocarbon block copolymer is an optionally hydrogenated copolymer comprising styrane blocks and comprising ethyleoe/C3 to C4alkylene blocks. Mention way be made, as preferably hydrogenated diblock copolymer, of styrene-ethyleaaie/propylene copolymers, styrene-ethyleae/butadiane copolymers or styrene-ethylane/butylene copolymers, Diblock polymers are sold in particular under the turns Kraton" O1701B by Kraton Polymers. i Mention may be made, as preferably hydrogenated triblock copolymers, of styrene-ethylene/propylene- styrene copolymers, styrene-ethylene/butadiene-styrene copolymers, styrene-isoprene-styrene copolymers or Btyrane-butadiene-styreae copolymers. Triblock polymers are sold in particular under the names Kraton* O1650B, Kraton* G1652, Kraton* Dl1Ol, Kraton* Diioa and Kraton* Bil60by Kraton Polymers. Use may in particular be made of a styrene-ethylene/butyleue-atyrene triblock copolymer. According to one embodiment of the invention, use may in particular be made of a blend of a styrene-butylene/ethylene-styreae triblock copolymer and of a styrene-ethylane/butylene diblock copolymer sold in particular uader the name Kraton* G3.657M by Kraton Polymers. Ose may also be made of a Mend of hydrogenated styrene~butylene/ethylene~styrene triblock copolymer and of hydrogenated ethylene-propylene- atyrene star polymer, such a blend being in particular an isododecane. Such blende are sold, for example, by Penreco under the trade names VerBagel* M5960 and Versagel* M5670. m Qrgawyoly^o**^ el+ffefyers The term "alastower" is understood to mean a flexible and deformable material having viscoelastic properties and in particular the consistency of a sponge or of a flexible sphere. Its modulus of elasticity is such that this material is resistant to deformation and has a limited ability to expend and to contract. This material is capable of returning to its original shape after it has been stretched. This elastomer is formed of polymeric chains of high molecular weight, the mobility of which is limited by a uniform network of crosslinking points. The organopolysiloxane elastomers used in the composition according to the invention are preferably solid and can be partially or completely crosslinked. When included in an oily phase, they are converted, according to the level of oily phase used, from a product with a spongy appearance, when they are used in the presence of low contents of oily phase, into a homogeneous gel in the presence of larger amounts of oily phase. The gelling of the oily phase by these elastomers can be complete or partial. The elastomers of the invention can be conveyed in the form of a gel composed of an organopolysiloxane elastomer which includes at least one hydrocarbon oil and/or one silicone oil and/or one fluorinated oil. In addition, the oily phase associated with the organopolysiloxane elastomer can be composed of this oil or these oils. The organopolyBiloxane elastomers used according to the invention can be chosen from the croselinked polymers described in Application BP-A-0235886. According to this patent application, they are obtained by an addition and crosslinking reaction, in the presence of a catalyst of the platinum type, of at leaBt: - (a) one organopolysiloxane having at least two lower alkanyl groups per molecule, these alkenyl groups comprising from two to six carbon atoros; and - (b) one orgaaopolyailoxane having at least two hydrogen atoms bonded to a silicone atom per molecule. The organopolysiloxane elastomers used in the composition of the invention can also be chosen from those described in Patent U8-A-S 266 321. According to this patent, they are chosen in particular from: - i) organopolysiloxanes comprising RaSiO and RSiOi.s units and optionally RjSiO0S and/or SiOa units, in which the R radicals, independently of one another, represent a hydrogen, an alkyl radical, such as methyl, ethyl or propyl, an aryl radical, such as phenyl or tolyl, or an unsaturated aliphatic group, such as vinyl, the ratio by weight of the RaSiO units to the RSiOi.s units ranging from 1/1 to 30/1; - ii) organopolysiloxanes which are insoluble and which can be swollen in the silicone oil, obtained by addition of an organohydropolysiloxane (1) and of an organopolysiloxane (2) having unsaturated aliphatic groups, so that the amount of hydrogen or of unsaturated aliphatic groups in (1) and (2) respectively is between 1 and 20 molt when the organopolysiloxane is not cyclic and between 1 and 50 mol% when the org«aopoly»ilojcane is cyclic. The organopolysiloxane elastomers used in the composition of the invention can, for example, be those sold under the names KSQ 6 by Shin-Btsu, Trefil E-505C or Trafil B-506C by Dow Corning or Granail (SR-CYC, SR DMF10, SR-DC556) by Grant Industries, or those sold in the form of already constituted gels: KSG 15, KSG 16, KSG 17, KSG 18, KSG 3«A, KSG 268, KSG 41, KSG 42, KSG 43 and KSG 44 of Sain-Etau, Granail SR 5CYC Gel, Granail SR DMF 10 Gel and Gransil SR DC556 Gel of Grant Industries, and 1229-02-187 and 1229-02-168 of General Electric. Use may also be made of a blend of silicone elastomers, in particular a blend of these commercial products. 8) Send.-crystalline polssssrs The term "polymer" is understood to mean compounds comprising at least two repeat units, preferably at least 3 repeat unitB and more especially at least 10 repeat units. The terra "semicrystalline polymer" is understood to mean polymers comprising a cryetallizable part, a crystallizable pendent chain or a cryetallizable block in the backbone, and an amorphous part in the backbone and exhibiting a first-order reversible phase change temperature, in particular a melting point (solid-liquid transition). When the crystallizable part is in the form of a crystallizable block of the polymeric backbone, the amorphous part of the polymer is in the form of an amorphous block; in this case, the semicrystalline polymer is a block copolymer, for example of the diblock, triblock or multiblock type, comprising at least one crystallizable block and at least one amorphous block. The term "block" is generally understood to mean at least 5 identical repeat units. The crystallizable block or blocks are then different in chemical nature from the amorphous block or block*. The semicrystalline polywer ha* a melting point of greater than or equal to 3Q°C (in particular ranging 5 from 30*C to 80*C) , preferably ranging from 30°C to 60°C. This melting point is a firat-order state change temperature. This melting point can be measured by any known method ) and in particular uaing a differential scanning calorimeter (DSC). Advantageously, the sewicryatalline polymer or polymers to which the invention applies exhibits a number- ; average molecular weight of greater than or equal to 1000. Advantageously, the seraicrystalline polymer or polymers of the composition of the invention have a number-average molecular weight Mn ranging from 2000 to 800 000, preferably fro* 3000 to 500 000, better still ) from 4000 to 150 000, in particular of less than 100 000 and better etill from 4000 to 99 000. Preferably, they exhibit a number-average molecular weight of greater ehan 5600, for example ranging from 5700 to 99 000. The term "cryafca.lliasable chain or block" is understood to mean, within the meaning of the invention, a chain or block which, if it were alone, would change reveraibly from the amorphous state to the crystalline state, according to whether the temperature is above or below the melting point. A chain within the meaning of the invention is a group of atoms which is in the pendent or side poeition with respect to the backbone of the polymer. A block is a group of atoms belonging to the backbone, a group constituting one of the repeat units of the polymer. Advantageously, the "crystallizable pendent chain" can be a chain comprising at least 6 carbon atoms. The semicrystalline polymer can be chosen from block copolymers comprising at least one crystallizable block and at least one amorphous block, homopolytnerB and copolymers carrying at least one crystallizable side chain per repeat unit, and their blends. Such polymer8 are described, document BP 1 3 96 259. for example, in the According to a more particular embodiment of the invention, the polymer results from a monomer comprising a crystallizafcle chain chosen from saturated Cn to C2} alkyl (meth)acrylates. Mention may be made, as specific example of structuring semi crystal line polymer 'which can be used in the composition according to the invention, of the Inteliwer* products from Landec, described in the "Intelimer* polymers" brochure, Landec IP22 (Rev. 4-97) . These polymers are in the solid form at ambient temperature (25 °C). The composition according to the invention comprises at least one ester of dextrin and of fatty acid(s). More particularly, it is a mono- or polyester of dextrin and of at least one fatty acid which corresponds in particular to the formula (C): (Formula Removed) in which: is an integer ranging from 3 to 200, in partiOular ranging f»o»n 20 to 150 and especially ranging from 25 to 50, the R1 R2 and R3 radicals, which are identical or different, are chosen from hydrogen or an acyl group (R-C0-) in which the R radical is a saturated or unsaturated and linear or breached hydrocarbon group having fro* 5 to 29, in particular from 7 to 21, especially from 11 to 19, more particularly from 13 to 17, and even 15, carbon atoais, with the proviso that at least one of the said Rl( Ra or Rj radicals is other than hydrogen. In particular, Ra, R3 and Ri can represent hydrogen or an acyl group (R-C0-) in which R is a hydrocarbon radical as defined above, with the proviso that at least two of the said Rj, Rj or R* radicals are identical and other than hydrogen. The combined Ri, Ra and Rj radicals can represent an acyl group (R-CO) which is identical or different and in particular identical. in particular, n advantageously varies frora 25 to 50 and in particular is equal to 38 in the general formula (C) of the ester accordlag to the invention. In particular when the R1, R2 and/or R3 radicals, which are identical or different, represent an acyl group (R-CO), these can be chosen from caprylic, capric, lauric, myristic, palmitic, stearic, arachic, behenic, isobutyric, isovaleric, 2-ethylbutyric, ethylmethylacetic, isoheptanoic, 2-ethylhexanoic, isononanoic, isodeeanoic, isotridecanoic, isomyristic, isopalmitic, isostearic, isoaracic, isohexanoic, decenoic, dodecenoic, tatradecenoic, myxistoleic, haxadecenoic, palmitoleic, oleic, elaidic, asclepinic, gondoleic, eicosonoic, sorbic, linoleic, linolenic, punicic, etearidonic, arachidonic, stearolic, eicosanyl and docosanoyl radicals, and their mixtures. Preferably, use ia made, as eBter of dextrin and of fatty acid(s), of at least a dextrin palaiitate. The latter can be used alone or as a mixture with other esters. Advantageously, the ester of dextrin and of fatty acid has a degree of substitution of less than or equal to 2.5 on the basis of one glucose unit, in particular varying from l.S to 2.5, preferably from 2 to 2.5. The weight-average molecular weight of the dextrin ester can in particular be from 10 000 to 150 00 0, in particular frowa 12 000 bo 100 000 and indeed even from 15 000 to 80 000. Dextrin esters, in particular dextrin palmitates, are available coftraercially under the name Rheopearl TL or Rheopearl KL frora Chiba flour. Waxes The composition according to the invention ia devoid of wax. The term *devoid of wax" is understood to mean a composition comprising less than 5% by weight, preferably less than 3t by weight, better still less than 2% by weight and even better still less than 1% by weight of wax, with respect to the total weight of the composition. More preferably, the coH$>oeition does not comprise wax. The wax under consideration in the context of the present invention is generally a lipophilic compound which is solid at ambient temperature (25°C) , which exhibits a reversible solid/liquid change in Btate and which has a melting point of greater than or equal to 30°C which can range up to 200°C and in particular up to 120°C. On bringing the wax to the liquid state (melting) , it i is possible to render it raiscible with oils and to form a microscopically homogeneous mixture but, on bringing the temperature of fctoe mixture back to ambient temperature, recrystalliBation of the wax in the oils of the mixture is obtained. In particular, the waxes can exhibit a melting point of greater than or equal to 45°C and in particular of greater than or equal to 55°C. Within the meaning of the invention, the melting point corresponds to the temperature of the most endotherraic peak observed by thermal analysis (DSC) aa described in the standard ISO 11357-3; 1999. The melting point of the wax can be measured using a differential scanning calorimeter (DSC), for example the calorimeter sold under the name *M0SC 2920" by TA Instruments. The measurement protocol is as follows: A 5 mg sample of wax placed in a crucible is subjected to a first rise in temperature ranging from -20"C to 100°C at a heating rate of 10*C/minute, is then cooled from 100°C to ~2G°C at a cooling rate of 10°C/minute and, finally, is subjected to a second riBe in temperature ranging from -20°C to 100«C at a heating rate of 5°C/minute. During the second rise in temperature, the variation in the difference in power absorbed by the empty crucible and by the crucible comprising the sample of wax is measured as a function of the temperature. The melting point of the compound is the value of the temperature corresponding to the tip of the peak of the curve representing the variation in the difference in power absorbed as a function of the temperature. The waxes can be of animal, vegetable, mineral or synthetic origin, and their mixtures, which are solid at ambient temperature. The waxes can, generally exhibit a hardness ranging from 0.01 MPa to 15 MPa, in particular of greater than 0.05 MPa and especially of greater than 0.1 MPa. The hardness is determined by the measurement of the compressive force measured at 20 °C using a texture analyser sold under the name TA-XT2 by Rheo, equipped with a Btainlees steel cylinder with a diameter of 2 row which is displaced at the measuring rate of o.l mm/e and which penetrates the wax to a penetration depth of 0.3 mm. The measurement protocol is as follows: The wax is melted at a temperature equal to the melting point of the wax + 10 °C. The molten wax is cast in a receptacle with a diameter of 25 mm and a depth of 20 mm. The wax is recrystallised at ambient temperature (25<>C) for 24 hours, so that the surface of the wax is flat and smooth, and than the wax is stored at 20°C for at least one hour before measuring the hardness or the tack. The rotor of the texture analyser is displaced at a rate of 0.1 mm/m and then penetrates the wax to a penetration depth of 0.3 on. When the rotor has penetrated the wax to the depth of 0.3 mm, the rotor is held stationary for 1 second (corresponding to the relaxation time) and is then withdrawn at the rate of 0.5 mm/s. The value of the hardness is the maximum compressive force measured divided by the surface area of the cylinder of the texture analyser in contact with the wax. The waxes can generally exhibit a weight-average molecular weight of leas than or equal to 3000, better still of leas than or equal to 2500 and even better still of las* than or equal to 2000. Mention may in particular be made, by way of illustration of waxes, of hydrooartoon waxes, such as beeswax, lanolin wax and Chinese insect waxes; rice bran wax, carnauba wax, cendelilla wax, ouricury wax, esparto wax, berry wax, shellac wax, Japan wax and sumac wax; montan wax, orange and lemon waxes, microcryatalline waxes, paraffin waxes and ozokerite,-polyethylene waxes, the waxes obtained by the Fischer-Tropsch synthesis and waxy copolymers, and their esters. Mention may also be made of waxes obtained by catalytic hydrogenation of animal or vegetable oils having linear or branched C»-C38 fatty chains. Mention may in particular be made, among these, of iaomerized jojoba oil, such as the transisomerized partially hydrogenated jojoba oil manufactured or sold by Desert Whale under the commercial reference lso-Jojoba~50*, hydrogenated sunflower oil, hydrogenated castor oil, hydrogenated coconut oil, hydrogenated lanolin oil and did, 1,1-triraethylolpropane) tatraatearate, aold under the name of Hest 2T-4S by Hefcereaa. Mention may also be made of silicone waxes or fluorinatad waxes. Use may also be made of the waxes obtained by hydrogenation of castor oil esterified with cetyl alcohol which are sold under the names of Phytowax Castor 16h64m and 22L73* by Sophira. Such waxes are described in Application FR-A-2 792 190. Mention may also be nwute ot waxen referred to as "tacky waxes", that is to say having a tack of greater than or equal to 0,1 N.a and a hardness of less than or equal to 3.5 MPa. The tacky wax ueed can have in particular a tack ranging from 0.1 N.s to 10 N.s, in particular ranging from o.l N.a to 5 N.s. preferably ranging from 0.2 to 5 N.s and better still hanging farom 0.3 to 2 N.s. The tack of the wax is determined by the measurement of the change in the force (cofflpressive force) as a function of the time at 20°C according to the protocol indicated above for the hardness. During the relaxation time of la, the force (cat!f>rassive force) strongly decreases until it becomes aero and then, during tlw withdrawal of the rotor, the force (stretching force) becomes negative to subsequently again increase towards the value 0. The tack corresponds to the integral of the curve of the force as a function of the time for the part of the curve corresponding to the negative values of the force. The value of the tack is expressed in N.s. The tacky wax which can be used generally has a hardness of leas than or equal to 3.5 MPa, in particular ranging from 0.01 MPa to 3.5 MPa, especially ranging from 0.05 MPa to 3 MPa. Use may be made, as tacky wax, of a C20-C40 alkyl (hydroxyBtearyloxy)stearate (the alkyl group comprising from 20 to 40 carbon atoms), alone or as a mixture. Such a wax is sold in particular under the names "Hester Wax K 82 P**, "Hydroxypolyester K 82 P*" and "Hester Wax K 80 P-" by Roster Keunen. (Formula Removed) The composition according to the invention can comprise at leaet one film-forming polymer. The film-forming polywer can be present in the composition according t© tha invention in a content of dry matter (or active material) ranging from 0.1% to 30% by weight, with respect to the total weight of the composition, preferably from 0.5% to 20% by weight and better atill from 1% to 15% by weight. In the present invention, the term "film-forming polymer" is understood to mean a polymer capable of forming, by itself alone or in the presence of an additional agent which is able to form a film, a continuous film which adheres to a support, in particular to keratinoua substances. The composition according to the invention can comprise at least one film-forming polymer which is fat-soluble (that is to say, soluble in a liquid fatty phase comprising oils or organic solvents, such as described above) or lipophilic (tbat is to say, compatible with a liquid fatty phase comprising oils or organic solvents, such as those described above). Mention may be made, as examples of fat-soluble polymer, of copolymers of vinyl ester (the vinyl group being directly connected to the oxygen atom of the ester group and the vinyl ester having a saturated and linear or branched hydrocarbon radical of 1 to 19 carbon atoms bonded to tha carbonyl of the ester group) and of at least one other monomer which can be a vinyl ester (other than tha vinyl ester already present), an oc-olefin (having from 8 to 28 carbon atoms) , an alkyl vinyl ether (the alkyl group of which comprises from 2 to 18 carbon atoms) or an allyl or methallyl ester (having a saturated and linear or branched hydrocarbon radical of 1 to 19 carbon atoms bonded to the carbonyl of the eater group). These copolymers can be crosslinked using croselinking agents which can be either of the vinyl type or of the allyl or raethallyl type, such as tetraallyloxyethane, divinylbensene, divinyl octanadioate, divinyl dodecane-dioate and divinyl octadecaoedioate. Mention may be made, as examples of these copolymers, of the following copolymers: vinyl acetata/allyl stearata, vinyl acetate/vinyl laurate, vinyl acetate/vinyl stearate, vinyl acetate/octadecene, vinyl acetate/octadecyl vinyl ether, vinyl propionate/allyl laurate, vinyl propionate/vinyl laurate, vinyl stearate/1-octadecene, vinyl acetate/1-dodecene, vinyl stearate/ethyl vinyl ether, vinyl propionate/cetyl vinyl ether, vinyl stearate/allyl acetate, vinyl 2,2-dimethyloctanoate/vinyl laurate, allyl 2,2-diraethylpentanoate/vinyl laurate, vinyl dimethyl- propionate/vinyl stearate, allyl dimethylpropioaate/vinyl stearate, vinyl propionate/vinyl stearate, croaslinked with 0.2* of divinylbenzane, vinyl dimathylpropionace/vinyl laurate, croaslinked with 0.2% of divinylbenzane, vinyl acetate/octadecyl vinyl ether, crosslinked with 0.2% of tetraallyloxyethane, vinyl acetate/allyl stearate, croaslinked with 0.2% of divinylbenzane, vinyl acetate/1-octadecene, croaslinked with 0.2% of divinylbenzena, and allyl propionate/allyl stearate, crosalinked with 0.2% of divinylbenzane. Mention may also be made, as fat-soluble film-forming polymers, of fat-soluble copolymers and in particular those resulting from the copolyroerization of vinyl eaters having from 9 to 22 carbon atoraa or of alkyl acrylates or methacrylates, the alkyl radicals having from 10 to 20 carbon atoms. Such fat-soluble copolymers can be chosen from copolymers of poly(vinyl stearata), of poly(vinyl staarate) crosslinked using divinylbenzeae, diallyl ether or diallyl phtbalate, copolymers of polyfstoaryl (meth)acrylate), of poly(vinyl laurate), of polydauryl (meth)acrylate), it being possible for these poly(math)aerylatee to be crosslinked using ethylene glycol dimethacrylatt or tetraethylene glycol dimethacrylate. The fat-soluble copolymers defined above are known and are described in particular in Application PR-A-2 232 303; they can have a weight-average molecular weight ranging from 2000 to 500 000 and preferably from 4000 to 200 000. Mention may also be made, as fat-soluble film-forming polymers which can be used in the invention, of polyalkylenee and in particular copolymers of c2-C20 alkenea, such as polybutene, alkylcelluloses with a saturated or unsaturated and linear or branched cx to C8 alkyl radical, such as ethylcellulose and propylcellulose, copolymers of vinylpyrrolidone (VP) and in particular copolymers of -vinylpyrrolidone and of Ca to C«o alkene and better still C3 to CJ0 alkene. Mention may be made, as examples of VP copolymer which can be used in the invention, of the VP/vinyl acetate, VP/athyl methacrylate, VP/ethyl meth-acrylata/raethacryllc acid, VP/eicosene, VP/hexadecene, VP/triacontene, VP/styrene or VP/acrylic acid/lauryl methacrylate copolymer or butylated polyvinylpyrrolidone (PVP). Mention may also be made of silicone resins, generally soluble or swellable in silicone oils, which are crosslinked polyorganosiloxane polymers. The nomenclature of silicone resins is known under the name of "MDTQ", che resin being described according to the various siloxane monomer units which it con$>rises, each of the letter* "MDTPQ* characterising one type of unit. Memtion may be made, as examples of cooiroercially available polyroethylaileeaquioxane resins, of those which are sold: by Waefcer under the reference Resin MK, auch as Belsil PMS MK; by Shin-Bteu under the reference KR-220L. Mention may be made, as siloxysilicate resins, of trifflethylsiloxysllicate (*TMS) resins, such as those sold under the reference SR1000 by General Electric or under the reference TMS 803 by Waeker. Mention may also be made of triasethylsiloxyailicate resins sold in a solvent, such as cyclomethicone, sold under the names "KF-7312J" by Shin-Btsu or "DC 749* or "DC 593" by Dow Corning. Mention may also be made of copolymers of silicone resins, such as those mentioned above, with polydimethylsiloxaaes, *u©h as the pressure-sensitive adhesive copolymers sold by Dow Corning under the reference BIO-PSA and described in the document as 5 162 410 or the silicone copolymers resulting from the reaction of a silicone resin, such as those described above, and of a diorganoalloxane, such as are described in the document WO 2004/073626. According to one embodiment of the invention, the film-forming polymer is a t ilm-fontiing linear block ethylenic polymer which preferably comprises at least one first block and at least one second block having different glass transition temperatures (Tg), the said first and second blocks being connected to one another via an intermediate block comprising at least one constituent monomer of the first block and at least one constituent monomer of the second block. Advantageously, the first and second blocke of the block polymer are incompatible with one another. Such polymers are described, for example, in the documents EP 1 411 069 or HO04/028488. The lipophilic or fat-soluble film-forming polymer can also be present in the composition in the form of particles in dispersion in a nonaqueous solvent phase which can be that of the composition according to the invention. The techniques for the preparation of these dispersions are well known to a person skilled in the art. Mention may be made, as examples of nonaqueous dispersions of film-forming polymer, of the dispersion described, for example, in the document EP 749 746 and in particular acrylic polymer particles, stabilized at the surface by a stabiliser, in dispersion in a fatty phase (for example isododecane), such as Mexomer PAP* from Chimex, or dispersions of particles of a grafted ethylenic polymer, preferably an acrylic polymer, in a liquid fatty phase, the ethylenic polymer advantageously being dispersed in the absence of additional stabilizer at the surface of the particles, such as described in particular in the document WO 04/055081. The film-forming polymer can also be provided in the form of particles in dispersion in an aqueous phase, such as, for example, acrylic dispersions, sold under the names Neocryl XK-90. Neocryl A-1070, Neocryl A-1090, Neocryl BT-62", Seocryl A-1079* and Neocryl A-523 by Avencia Neoresins, Dow Latex 432* by Dow Chemical, Daitosol 5000 AD or Daitosol 5000 SJ* by Paito Kaaey Kogyo or Syntran 5760 by Interpolymer, or aqueous dispersions of polyurethane, sold under the names Neorez R-981 and Neorez R-974 by Avecia-Neoresins, Avalure UR-40S, Avalure UR-410, Avalure UR-425*, Avalure UR-4S0, Saacure 875*, Sancure 861, Sancure 878* and Sancure 2060 by Goodrich, Impranil 85® by Bayer, Aigusntere H-1511 by Hydromer; sulphopolyeetere, sold under the trade name B&stman AQ0 by Eastman Chemical Products, vinyl dispersions, such as Mexomer P*M* from Cktwex and their blends. The composition according to the invention can comprise a plasticizing agent favourable to the formation of a film with the film-forming polyner. Such a plaaticizing agent can be chosen from any compound known to a person skilled in the art as being capable of fulfilling the desired role. Colouring material The composition according to the invention can also comprise at least one colouring material, such as pulverulent materials, fat-soluble dyes or water-soluble dyes. The pulverulent colouring materials can be chosen from pigments and pearleecent agents. The pigments can be white or coloured, inorganic and/or organic and coated or ooncoated. Mention may be made, among inorganic pigments, of titanium dioxide, optionally treated at the surface, zirconium, zinc or cerium oxides, and also iron or chromium oxides, manganese violet, ultramarine blue, chromium hydrate and ferric blue. Mention may be made, among organic pigments, of carbon black, pigraentB of D & C type and lakes, based on cochineal carmine, of barium, strontium, calcium or aluminium. The pearleecent agents can be chosen from white pearleacent pigments, such as mica covered with titanium oxide or with bismuth oxychloride, coloured pearlescent pigments, such as titanium oxide-coated mica with iron oxides, titanium oxide-coated mica with in particular ferric blue or chromium oxide or titanium oxide-coated mica with an organic pigment of the abovementiomd type, and pearlescent pigments based on bismuth oxychloride. The fat-soluble dyes are, for example, Sudan resd, D&C Red 17, D$C Green 6, ^-carotene, soybean oil, Sudan brown, DfcC Yellow 11, D$c Violet 2, D&C Orange 5, quinoline yellow or anoatto. These colouring materials can be present in a content ranging from 0.01 to 30% by weight, with respect to the total weight of the composition. Fillers The composition according to the invention can additionally comprise at least one filler. The fillers can be cho»*n from those well known to a person skilled in the art and commonly used in cosmetic compositions. The fillers can be inorganic or organic and lamellar or spherical. Mention may be made of talc, mica, silica, kaolin, powders formed of polyamide, such as Nylon*, sold under the name orgasol* by Atochem, of poly-§-alanine and of polyethylene, powders formed of tetrafluoroethylene polymers, such as Teflon*, lauroyllysine, starch, boron nitride, hollow polymer microspheres which are expanded, such as those of poly(vinylidene chloride)/acrylonitrile, for example chose sold under the name Expancal* by Nobel Industrie, acrylic powders, such as those sold under the name Polytrap* by Dow Corning, particles formed of polymethyl methacrylata and silicone resin microbeads (Tospearls* from Toshiba, for example), precipitated calcium carbonate, magnesium carbonate, basic magnesium carbonate, hydroxyapatite, hollow silica microspheres (Silica Beads* from Mapreeos), glass or ceramic microcapsules, or metal soaps derived from organic carboxylic acids having from 8 to 22 carbon atoms and in particular from 12 to 18 carbon atoms, for exawple zinc stearate, magnesium stearate, lithium stearate, sine laurate or magnesium myristate. Use may also be made of a compound capable of swelling whan heated and in particular of heat-expandable particles, such as nonexpanded microspheres formed of vinylidene chloride/acicylonitrile/methyl methacrylate copolymer or of copolymer of horaopolymer of acrylonitrile, auch as, for example, those sold respectively under the references Bxpancel* 820 DU 4 0 and Bxpancel* 007Wu by Akeo Hobel. The fillers can represent from 0.1 to 25* by weight, in particular from 1 to 20% by weight, with respect to the total weight of the composition. Aqueous pfaaea The composition according to the invention can comprise water and/or water-soluble solvent(s) which can be introduced as such into the formulation according to the invention or can be incorporated therein via one or more ingredients constituting the said composition. Thus, water can in particular be introduced into the composition via the introduction of a latex or pseudolatex, that is to say of an aqueous dispersion of polymer particles. The water-raiacible solvents (miecibility in water of greater than 50% by weight at 25°C) are in particular lower monoalcoholB having from 1 to 5 carbon atoms, such as ethanol or isopropanol, glycols having from 2 to s carbon atoms, such as propylene glycol, ethylene glycol, 1,3-butylene glycol or dipropylene glycol, C3-C4 ketones, C2-C4 aldehydes and their mixtures. Advantageously, the composition exhibits a content of water and/or water-soluble solvent (s) of less than or equal to 15% ' by weight, with respect to the total weight of the composition, preferably of lese than or equal to 10% by weight, better still of less than or equal to 5% by weight and even, better still of less than or equal to 3% by weight. According to one ewbodinent, the composition according to the invention is devoid of water (anhydrous composition). fibres The composition according to the invention can additionally comprise fibres which make possible an improvement in the lengthening effect. The term "fibre" should be understood as meaning an object with a length L and a diameter D such that L is much greater than D, D being the diameter of the circle in which the cross section of the fibre is framed, in particular, the L/D ratio (or aspect ratio) is chosen within the range from 3.5 to 2500, in particular from 5 to 500 and more particularly from 5 to 150. The fibres which can be used in the composition of the invention can be fibres of synthetic or natural and inorganic or organic origin. They can be short or long, individual or organized, for example plaited, and hollow or solid. They can have any shape and can in particular be circular or polygonal (square, hexagonal or octagonal) in cross section, according to the specific application envisaged. In particular, their ends are blunted and/or polished to prevent injury. in particular, the fibres have a length ranging from l um to 10 tan, in particular from 0.1 tin to 5 mm and more particularly from 0.3 mm to 3.S mm. Their cross section can be included within a circle with a diameter ranging from 2 nra to 500 um, in particular ranging from 100 nm to 100 inn and wore particularly ranging from 1 pi to 50 pm. The weight or count of the fibres ia often given in denier or decitex and represents the weight in grants per 9 km of yarn. The fibres according to the invention can in particular have a count chosen within the range from 0.1S to 30 denier and especially from 0.18 to 18 denier. The fibres which can be used in the composition of the invention can be chosen from rigid or nonrigid fibres. They can be of synthetic or natural and inorganic or organic origin. Furthermore, the fibres may or may not be surface treated, may or may not be coated and may or may not be coloured. Mention may be made, as fibres which can be used in the composition according to the invention, of fibres which are not rigid, such as polyamide (Nylon*) fibres, or fibres which are rigid, such as polyimidearoide fibres, for example those sold under the Kennel* or Kennel Tech* names by Rhodia, or poly(p-phenylene tereph-thalawide) (or aramid) fibres, sold in particular under the Kevlar* name by DuPont de Newours. The fibres can be present in the composition according to the invention in a content ranging from 0.01% to 10% by weight, with respect to the total weight of the composition, in particular from 0.1* to 5% by weight and more particularly from 0.3% to 3% by weight. Co—tig active principles Mention may in particular be made, as cosmetic active principles which can be used in the compositions according to the invention, of antioxidants, preservatives, fragrances, neutralizing agents, emollients, moisturizing agents, vitamins and screening agents, in particular sunscreens. Of course, a person skilled in the art will take care to choose the optional additional additives and/or their amounts BO that the advantageous properties of the composition according to the invention are not, or not substantially, detriieentally affected by the envisaged addition. The composition before expansion in volume can be provided in the suspension, dispersion, solution or gel form. Preparation proeees The compositions employed in the invention can be prepared by processes for mixing, stirring or dispersing compressed gases, such as air, chlorofluorocarbon-based compounds, nitrogen, carbon dioxide, oxygen or helium, a process for mixing and stirring in the preeence of a foaming agent, such as a surfactant. In particular, the composition is prepared by mixing the ingredients with stirring, generally under hot conditions, and by then expanding in volume under the action of a gae, it being possible for the gaB to ba introduced during the stage of cooling the composition or after preparation of the composition, for example using a device for expanding in volume of Mondomix type, a beater of Kenwood type, a scraped-surface exchanger or a dynamic mixer {of IMT type, for example). The gas is preferably air or nitrogen. The composition according to the invention can be packaged in a container delimiting at leaat one compartment which comprises the said composition, the said container being closed by a closure part. The container can be equipped with a means for the dispensing of the said product. In particular, the container can be equipped with a pump. The container can be a pot. The container can be at least partly made of thermoplastic. Mention may be made, as examples of thermoplastics, of polypropylene or polyethylene. Alternatively, the container is made of nonthermoplastic material, in particular of glass or metal (or alloy). The composition can be applied by finger or using an applicator. The container is preferably used in combination with an applicator comprising at least one application component configured in order to apply the composition to teeratinoua substances. According to another advantageous embodiment, the applicator comprises an application nozzle. gxaJPT-yg The examples which follow are presented by way of illustration and without limitation of the invention. Unless otherwise indicated, the amounts are given as per cent by weight. Example 1 to 5» lipetons in the foam form The following lipstick compositions according to the invention are prepared: (Table Removed) Procedure The oily structuring agent, the oil and the pigments are heated to 80°C in a jacketed beaker with stirring of deflocculating paddle type. The tnolten mixture is poured into a device for expanding in volume of "Mondoraix" type using a peristaltic pump at a flow rate of 6 kg/h; the inlet temperature of the mixture displays 57C and the product is expanded in TOlutne in the mixing head, which is thermostatically controlled at 20°C. At the outlet of the device for expanding in volume, the foam, the temperature of which is 30C, is packaged in pots which are iamediately placed for 20 minutes in a chamber thermostatically controlled at -280C. For each of the cowpoaitiona, the parameters of density and of degree of expansion in volume were measured according to the protocol! described above. The results are presented in the following table: (Table Removed) The procedure used is the same as for the compositions of Examples 1 to 5 above. The parameters of density and of degree of expansion in volume volume of the composition were measured according to the protocols described above. (Table Removed) Kxaasjles 7 to 101 Colowty— s cosajoeitiona The following conpositiona were prepared: (Table Removed) The procedure used is the same as for the compositions of Bxawples 1 to 5 above. The parameters of density and of degree of expansion in volume of each composition were measured according to the protocols described above. (Table Removed) The procedure used is the saute as for the compositions of Examples 1 to 5 above. The parameters of density and of degree of expansion in volume of each composition were measured according to the protocols describe (Table Removed) The procedure used is the same as for the compositions of Examples 1 to 5 above. The parameters of density and of degree of expansion in volume of each composition were measured according to the protocols described above. (Table Removed) 1. Cosmetic composition in the foam form coragprising a continuous oily phase and at least one structuring agent for the oily phase, the said coB^josition being devoid of wax. 2. Composition according to Claim 1, characterized in that it exhibits a density of less than or equal to 0.95. 3. Composition according to Claim 2, characterized in that it exhibits a density of lass than or equal to 0.9, better still of less than or equal to 0.8. 4. Composition according to Claim 2 or 3, characterized in that it exhibits a density of greater than or equal to 0.2 and better still of greater than or equal to 0.3. 5. Composition according to one of the preceding claims, characterized in that it exhibits a degree of expansion in volume of greater than or equal to 10%. 6. Composition according to Claim 5, characterized in that it exhibits a degree of expansion in volume of less than 350%. 7. Composition according to Claim 5 or 6, characterized in that it exhibits a degree of expansion in volume ranging from 10% to 3 00%, preferably from 30% to 250% and better still from 40% to 200%. 8. Composition according to one of the preceding claims, characterized in that the structuring agent or agents for the oily phase are present in a content ranging from 0.1 to 60% by weight, with respect to the total weight of the composition, better atill from 0.5 to 50* by weight and even better still from 1 to 40% by weight. 9. Composition according to one of the preceding claims, characterised in that the structuring agent for the oily pitas* is chosen from: A) silicone polymers comprising at least one unit comprising: 1) polyorganosiloxanes comprising at least two groups capable of establishing hydrogen interactions, these two groups being situated in Che chain of the polymer, and/or 2) polyorganosiloxanes comprising at least two groups capable of establishing hydrogen interactions, these two groups being situated on grafts or branchings, the said groups capable of establishing hydrogen interactions being chosen from ester, amide, sulphcmawide, carbamate, thiocarbamate, urea, urethane, thiourea, oxaraido, guanidino and biguanidino groups and their combinations, B) polyaraide polymers comprising a) a polymeric backbone having hydrocarbon repeat units provided with at least one nonpendent amide unit and, optionally, b) at least one optionally functionalized pendent fatty chain and/or at least one optionally functionalized end fatty chain which comprise at least 4 carbon atoms and which are bonded to these hydrocarbon units, c) olefin copolymers, D) organopoly8iloxan« elastomers, E) aamicrystalline polymers, F) esters of dextrin and of fatty acid, and their blends. 10. Composition according to the preceding claim, in which the silicon* polymer comprises at least one unit corresponding to the formula: in which: (Formula Removed) 1) R4, 8s, R* and R7, which are identical or different, represent a group chosen from: - saturated or unsaturated and linear, branched or cyclic Cx to C*» hydrocarbon groups which can comprise, in their chain, one or more oxygen, sulphur and/or nitrogen atoms and which can be substituted, partially or completely, by fluorine atoms, - cs to c10 aryi groups optionally substituted by one or more Ca to C* alkyl groups, - polyorganosiloxan* chains comprising or not comprising one or more, oxygen, sulphur and/or nitrogen atoms, 2) the X groups, which are identical or different, represent a linear or branched Ci to C30 alkylanediyl group which can comprise, in its chain, one or more oxygen and/or nitrogen atoms, 3) Y is a Gi to Cso alkylene (linear or branahed), arylene, cycloalkylene, alkylarylene or arylalkylene divalent group, saturated or unsaturated, which can comprise one or more oxygen, sulphur and/or nitrogen atoms and/or carry, as substituent, one of the following atoms or groups of atoms: fluorine, hydroxyl, Cj to C8 cycloalkyl, Ca to C<© alkyl, C5 to C10 aryl, phenyl optionally substituted by 1 to 3 groups of the type Ci to Cj alkyl, Ci to C3 hydroxyalkyl and C3 to Cs aminoalkyl, or 4) Y represents a group corresponding to the formula: (Formula Removed) in which: - T represents a saturated or unsaturated and linear or branched trivalent or tetravalent C3 to Cj4 hydrocarbon group which is optionally substituted by a polyorgaooBiloxane chain and which can comprise one or more atoms chosen from 0, N and S, or T represents a trivalant atom chosen from N, P and Al, and - R* represents a linear or branched Ci to CSo alkyl group or a polyorganoailoxane chain, which can comprise one or more ester, amide, urethane, thiocarbamate, urea, thiourea and/or sulphonamide groups, which may or may not be bonded to another chain of the polymer, 5) the G groups, which are identical or different, represent divalent groups chosen from: (Formula Removed) where R* represents a hydrogen atom or a linear or branched Ci to Cao alkyl group, provided that at least 50* of the R* groups of the polymer represent a hydrogen atom and that at least two of the G groups of the polymer are a group other than: and 6)n ie an integer ranging from 2 to 500, preferably from 2 to 200, and ra is an integer ranging from 1 to 1000, preferably from 1 to 700 and better still from 6 to 200. 11. Composition according to Claim 10, in which Y represents a group chosen from: a) linear Cj to C30, preferably Cx to Ci0, alkylene groups, b) branched CJ0 to CM alkylene groups which can comprise rings and nonconjugated unsaturations, c) C«-C« cycloalkylene groups, d) phenylene groups optionally substituted by one or more ca to C«B alkyl groups, a) Ci to Cao alkylene groups comprising from 1 to 5 amide groups, f) Cx to Cao alkylene groups comprising one or more substitueats chosen from hydroxyl, Cj to cB cycloalkane, Ci to Cs hydroxyalkyl and Ci to Ce alkylaraine groups, g) polyorganoailoxane chains of formula: (Formula Removed) in which R*, RB, Rs, R7, T and m are as defined in Claim 10, and h) polyorganoailoxane chains of formula: (Formula Removed) 12. composition according to any one of Claims 9 to 11, in which the folymer comprises at least one unit of formula (III) or (IV) r (Formula Removed) in which R4, R*, R*( Rr, X, Y, m and n are as defined in Claim 10. 13. Composition according to one of Claims 10 to 12, in which X and/or Y represent an alkylene group comprising, in its alkylene part, at least one of the following components.- 1) 1 to 5 amide, urea, urethane or carbamate groups, 2) a Cs or C« cycloalkyl group, and 3) a phenyls** group optionally substituted by 1 to 3 identical or different Ci to C3 alkyl groups, and/or substituted by at least one component chosen from the group consisting of: - a hydroxy1 group, ■ a Cj to C» cycloalkyl group, - one to three C% to C«« alkyl groups, - a phenyl group optionally substituted by one to three Ci to Cj alkyl groups, - a Ci to Cj hydtetacyalkyl group, and - a ca to C« awino«lkyl group. 14. Composition accordin® to any one of Claims 10 to 13, in which Y represents: (Formula Removed) where R8 represents a polyorganosiloxaae chain and T represents a group of formula: (Formula Removed) in which a, b and c are independently integers ranging from 1 to 10 and R13 is a hydrogen atom or a group such as those defined for R*, R8, R8 and R7 in Claim 10, 15. Conyosition according to any one of Claims 10 to 14, in which R*, R\ R* and R7 independently represent a linear or branched Ct to C40 alkyl group, preferably a di3, CaHs, n-C3H7 or iaopropyl group, a polyorganosiloxane chain or a phenyl group optionally eubstituted by one to three methyl or ethyl group*. 16. Composition according to Claim 10, characterized in that it comprises at least one polydimethylsiloxane block polymer of general formula (I) having an index m of approximately 100. 17. Composition according to one of the preceding claims, characterised in that the structuring agent is chosen frott polyamide polymers comprising a) a polymer backbone having hydrocarbon repeat units provided with at least one nonpendent amide unit and, optionally, b) at least one optionally functionalised pendent fatty chain and/or at least one optionally functionalized end fatty chain which comprise at least 4 carbon atoms and which are bonded to these hydrocarbon units. 18. Composition according to the preceding claim, characterised in that the fatty chains represent from 40 to 98% and better still from 50 to 95* of the total number of the amide units and fatty chains. 19. Composition according to either of Claims 17 and 18, characterised in that the fatty chains comprise from 6 to 120 carbon atoms and better still from 8 to 120 carbon atoms. 20. Composition according to one of Claims 17 to 19, characterized in that the pendent fatty chains are bonded directly to at least one of the nitrogen atoms of the amide units. 21. composition according to one of Claims 17 to 20, characterized in that the weight-average molar mass of the polyamide is less than 100 000. 22. Composition according to one of Claims 17 to 21, characterised in that the weight-average molar mass of the polyawide range* from 1000 to 100 000, preferably from 1000 to 50 000 and better still from 1000 to 30 000. 23. Composition according to one of Claims 17 to 22, characterized in thmt the end fatty chain or chains are bonded to the backbone via bonding groups. 24. Composition according to Claim 23, characterized in that the bonding groups are ester groups. 25. Composition according to one of Claims 17 to 24, characterised in that the fatty chain or chains comprise from 12 to 68 carbon atoms. 26. Composition according to one of Claims 17 to 25, characterised in that: the polyamide is chosen from polyamides of following formula (A): (Formula Removed) in which: - n is an integer ranging from 1 to 30, R'i independently represents, in each case, a fatty chain and is chosen from an alkyl or alkenyl group having at least 1 carbon atom and in particular from « to 24 carbon atoms; R'2 independently represents, in each case, a hydrocarbon radical comprising from 1 to 52 carbon atoms; R'3 independently represents, in each case, an organic group coe*>**ising at least one atom chosen from carbon, hydrogen or nitrogen atoms, provided that R'j comprises at least 3 carbon atoms; R't independently represents, in each case: a hydrogen atom, an alkyl group comprising from 1 to 10 carbon atom* or a direct bond to at least one group chosen from R'j and another R'*, so that, when the »aid group is another R'4, the nitrogen atom to which both R'3 and R'« are bonded forme part of a heterocyclic structure defined by R'^-N-R'j, provided that at least 50% of the R'< group* represent a hydrogen atom, and - L represents a bonding group chosen from ester, ether, amine, urea, urothane, thioester, thioether, thiourea and thiourethane groups, optionally substituted by at least one R'I group. 27. Composition according to one of claims 17 to 26, characterized in that the polyamide is chosen from polyaraides of following formula (B): (Formula Removed) in which: - m denotes an integral number of amide units such that the number of ester groups represents from 10% to 50% of the total number of the ester and amide groups; - Ri is in each case independently an alkyl or alkenyl group having at least 4 carbon atoms and in particular from 4 to 24 carbon atoms; R, independently represents, in each case, a C« to C«a hydrocarbon group, provided that 50% of the R3 groups represent a CJB to c« hydrocarbon group/ Ri independently represents, in each case, an organic group provided with at least 2 carbon atoms, with hydrogen atom* and optionally with one or more oxygen or nitrogen atoms; and R, independently represents, in each case, a hydrogen atom, a d. to CJ0 alkyl group or a direct bond to »i or to another R4, so that the nitrogen atom to which both R3 and R« are bonded forms part of a heterocyclic structure defined by R4-N-R3, with at least 50% of the R, groups representing a hydrogen atom. 28. Composition according to one of the preceding claims, characterised in that the structuring agent is chosen from olefin copolymers. 29. Composition according to the preceding claim, characterized in that the olefin copolymer is a block copolymer chosen from diblock, triblock, multiblock, radial and star copolymers and their blends. 30. Composition according to Claim 28 or 29, characterised in that the olefin copolymer is chosen from hydrocaifcon block copolymers formed by a polymerization of monomers having in particular one or two athylenic uneaturations and having from 2 to 5 carbon atoms. 31. Composition according to one of Claims 28 to 30, characterized in that the copolymer is chosen from copolymers formed by a polymerization of styrene and of olefin, the olefin being chosen from ethylene, propylene, butadiene or isoprene. 32. Composition according to one of Claims 28 to 31, characterised in that the olefin copolymer is chosen from optionally hydrogenated copolymers comprising styrana blocks and comprising ethylene/C3-C« alkylene blocks. 3. Composition according to any one of Claims 28 to 32, characterised in that the oily structuring agent is chosen from styre&e-butylene/ethyleae-styreae triblock copolymers. 4. Composition according to any one of the preceding claims, characterised in that it comprises a structuring agent chosen from esters of dextrin and of fatty acid. 5. Composition according to Claim 34, characterized in that the eater of dextrin and of fatty acid