Land of Terror: (#6) (Pellucidar Series)

Years ago David Innes and Abner Perry bored straight down through five hundred miles of the earth's crust and landed in Pellucidar, the savage, primeval world that lies at the center of the earth. This is the story of their continuing adventures in the timeless land of perpetual noon and their encounters with the hideous creatures and savage men who pursue them. Although they encounter enemies at every turn, David and Abner find a few loyal friends as they embark on exhilarating adventures.