  Let C be a smooth curve, and M_r(C) the coarse moduli space of vector bundles
of rank r and trivial determinant on C. We examine the generalized Verschiebung
map V_r: M_r(C^(p)) --> M_r(C) induced by pulling back under Frobenius. Our
main result is a computation of the degree of V_2 for a general C of genus 2,
in characteristic p>2. We also give several general background results on the
Verschiebung in an appendix.
