Pellucidar

Boring 500 miles through the earth's crust in their "iron mole," David Innes and Professor Perry make the astonishing discovery that the earth's center is hollow and the site of an amazing interior world -- Pellucidar! It is at a Stone Age level of development, dominated by chilling reptilian monsters with a high degree of intelligence who communicate through extrasensory means. Evolution is proceeding along different lines in Pellucidar than it did on the Earth's surface, and human beings ...