Above, a cinerous tortoise seen from above and below; middle, a galeated tortoise seen from above; below, a lettered tortoise seen from above and below. Etching by Hill.

Licence: Public Domain Mark

Credit: Above, a cinerous tortoise seen from above and below; middle, a galeated tortoise seen from above; below, a lettered tortoise seen from above and below. Etching by Hill. Wellcome Collection. Source: Wellcome Collection.