When the marine forms of life are spoken of as having changed simultaneously throughout the world, it must not be supposed that this expression relates to the same year, or even to the same century, or even that it has a very strict geological sense; for if all the marine animals now living in Europe, and all those that lived in Europe during the pleistocene period (a very remote period as measured by years, including the whole glacial epoch) were compared with those now existing in South America or in Australia, the most skilful naturalist would hardly be able to say whether the present or the pleistocene inhabitants of Europe resembled most closely those of the southern hemisphere.
Itsas bizi-formak mundu guztian aldi berean aldatu direla esaten denean, ez da uste izan behar adierazpen honek urte berean, ezta mende berean ere esan nahi duenik, ezta adiera geologiko hertsirik duenik ere; izan ere, baldin egun Europan bizi diren animalia guztiak eta aldi pleistozenoan-urtez neurturik aldi oso urruna berau, glaziaraldi guztia hartzen duena-Europan bizi izan ziren guztiak egun Hego Amerikan edo Australian bizi direnekin konparatuko balira, naturalistarik trebeenak ere nekez esan ahal izanen luke Europako egungo ala pleistozenoko biztanleak diren hego hemisferiokoen antz handiena dutenak.