  We have investigated the peculiarities of nuclear descent from a parabolic
fission barrier within a generalized Langevin equation with power--law
$f(t-t')=(|t-t'|/\tau)^{-\alpha}$ memory function. We have observed much
stronger slowing down of the nuclear descent in the presence of long--range
memory effects, caused by the power--law memory function at $0<\alpha<1$, than
in the presence of short--range memory effects, generated by exponential
$f(t-t')={\rm exp}(-|t-t'|/\tau)$ memory function. At a specific value of the
exponent $\alpha=1/2$ of the power--law memory function, it turned out possible
to find analytically the trajectory of the descent and demonstrate that the
long--range memory effects give rise to complex time oscillations of nuclear
shape, becoming more frequent and damped with the correlation time $\tau$. We
have found fairly long ($>10^{-20}~{\rm s}$) times of the descent of $^{\rm
236}{\rm U}$ at the values of the correlation time $\tau \sim [10^{-24}\div
10^{-23}]~{\rm s}$.
