(Unofficial and official electronic versions are available online.)

In the appendix to this paper I prove a conjecture of Maisner and Nart:
namely, that if *k*
is a finite field with *q* elements, then there is no
curve of genus 2 over *k* whose Jacobian has characteristic
polynomial of Frobenius
*x*^{4} + (1 − 2*q*) *x*^{2} + *q*^{2}.