Let
W
p
{W_p}
stand for a compact Riemann surface of genus p. (1) Let
W
q
{W_q}
be hyperelliptic, and let n be a positive integer. Then there exists an unramified covering of n sheets,
W
p
→
W
q
{W_p} \to {W_q}
, where
W
p
{W_p}
is hyperelliptic. (2) Let
W
2
n
+
1
→
W
2
{W_{2n + 1}} \to {W_2}
be an unramified Galois covering with a dihedral group as Galois group, and let n be odd. Then
W
2
n
+
1
{W_{2n + 1}}
is elliptic hyperelliptic (bi-elliptic). (3) Let
W
4
→
W
2
{W_4} \to {W_2}
be an unramified non-Galois covering of three sheets. Then
W
4
{W_4}
is hyperelliptic.