The low-lying octupole states of the doubly even deformed nuclei with 152 ≦ A ≦ 190 are studied. The pairing + a modified octupole-octupole force is utilized as residual interaction. The ordering of states with different K-quantum numbers is analysed in terms of the shell-model orbits filled. The problem of admixtures of the c.m. motion into the octupole states is investigated. The quasiparticle random phase approximation (RPA) equations are solved and in each nucleus the lowest K π = 0 −, 1 −,2 −,3 − states are obtained. Then, the Coriolis interaction matrix elements between states with K and K + 1 are calculated and the corresponding matrix is diagonalized. The resulting energies and B(E3) values are compared with the experimental data. The agreement is surprisingly good. It turns out that the inclusion of the Coriolis coupling is very essential for the explanation of the B(E3) values and the energy intervals within the rotational bands. The modification of the octupole-octupole force makes it possible to use interaction constants practically independent of the K-value.