We must be cautious in attempting to correlate as strictly contemporaneous two formations, which do not include many identical species, by the general succession of the forms of life.
Kontuz jokatu behar dugu, forma organikoen hurrenketa orokorra bide, espezie berdin-berdin askorik ez duten bi formazioren artean garaikidetasun hertsiko korrelazioa jartzen saiatzean.