In The Geographical Distribution of Animals (1876) he wrote, "We live in a zoologically impoverished world, from which all the hugest, and fiercest, and strangest forms have recently disappeared".
Dalam The Geographical Distribution of Animals (1876) ia menulis, "Kita hidup dalam suatu dunia yang miskin secara zoologi, di mana semua bentuk yang paling besar, dan paling ganas, serta paling aneh telah menghilang baru-baru ini."