Abstract
A Cartan space is a pair $(M,K)$, where $M$ is a smooth manifold and $K$
an Hamiltonian on the slit cotangent bundle $T_0^{*}:=TM\ \{(x,0), x\in M\}$ that is positively homogeneous of degree $1$ in momenta. We show
that $K$ induces an almost $2$-paracontact Riemannian structure on $T_0^{*}$
whose restriction to the ¯guratrix bundle $\mathbb{K} =\{ (x,p)| K(x,p)=1 \}$
is an almost paracontact structure. A condition for this almost para-
contact structure to be normal is found, and its geometrical meaning is
pointed out. Similar results for Finsler spaces can be found in [1] and
[3].