  The non-relativistic dynamics of a spin-1/2 particle in a monopole field
possesses a rich supersymmetry structure. One supersymmetry, uncovered by
d'Hoker and Vinet, is of the standard type: it squares to the Hamiltonian. In
this paper we show the presence of another supersymmetry which squares to the
Casimir invariant of the full rotation group. The geometrical origin of this
supersymmetry is traced, and its relationship with the constrained dynamics of
a spinning particle on a sphere centered at the monopole is described.
