but it is possible that the progenitors of these several species, while they were furnished with eyes, may formerly have ranged over both continents, and then have become extinct, excepting in their present secluded abodes.
baina daitekeena da espezie ezberdin hauen arbasoak, begiz horniturik zeudenean, lehenik kontinente bietan zehar hedatu eta gero iraungi izana, gaur bizi diren leku apartatuetan izan ezik.