The travelers, en route to the center of the earth, see exotic creatures not found on the surface of the planet. For example, they view living dinosaurs, such as an Ichthyosaurus and a Plesiosaurus having a fight. They also see very large insects and mastodons. In fact, they come across a whole herd of mastodons, exactly like those discovered as fossils in Ohio in 1801.
They also see a very large man who is perhaps twelve feet tall. He has a head the size of a buffalo head and lots of matted hair. The voyagers are not entirely sure if he is a man, an ape-man, or some member of the monkey family, but they avoid having any contact with him.
They also find the plant life of the earth's surface all jumbled together:
there appeared confounded together and intermixed, the trees of such varied lands, specimens of the vegetation of every part of the globe; there was the oak near the palm tree, the Australian eucalyptus, an interesting class of the order Myrtaceae—leaning against the tall Norwegian pine, the poplar of the north, mixing its branches with those of the New Zealand kauris.