Burroughs's Tarzan books have given rise to many motion pictures and other adaptations, and they are constantly being reprinted in paperback, finding a ready readership among young and old. Tarzan is a far more vivid figure than any of the characters in The Land That Time Forgot and has become so well known that even people who have never read a Tarzan book know who he is. He has become a fundamental part of modern culture. The books about Pellucidar, the world in the center of the earth, have much in common with The Land That Time Forgot. This series features first-person narrators, a wild and savage world, a variety of human races, monstrous beasts unique to it, and creatures recognizable from the surface world's past, such as dinosaurs.

Evolution is again a theme in the Pellucidar books, because the world within the earth has followed...