  The main thrust of present note is a volume formula for hyperbolic surface
bundle with the fundamental group G.
  The novelty consists in a purely algebraic approach to the above problem.
Initially, we concentrate on the Baum-Connes morphism m(G): K(BG)--> K(C*G) for
our class of manifolds, and then classify m(G) in terms of the ideals in the
ring of integers of a quadratic number field K. Next, we extract the
topological data (e.g. volume of the orbifold H/G) from the arithmetic of field
K.
