Strange fishes, lizards, birds, and uncouth beasts,
Worlds of strange life, but all in ordered grades,
World over world, each tombed in its own age
Or merging into the next with subtle changes,
Delicate modulations of one form,
(Urged by what force? Impelled by what dark power?)
Progressing upward, into subtler forms
Through all the buried strata, till there came
Forms that still live, still fight for life on earth,
Tiger and wolf and ape; and, last of all,