  We study Abelian ideals of a Borel subalgebra consisting of long roots. It is
shown that methods of Cellini and Papi can be extended to this situation. A
uniform expression for the number of long Abelian ideals is given. We also show
that there is a one-to-one correspondence between the long Abelian ideals and
B-stable commutative subalgebras in the little adjoint representation of the
Langlands dual Lie algebra.
