Pellucidar by Edgar Rice Burroughs [Pellucidar #2]

This Halcyon Classics ebook is the second of Edgar Rice Burroughs' Pellucidar series, PELLUCIDAR.

A classic of "hollow Earth" fiction, PELLUCIDAR tells of the continuing adventures of two unwilling adventurers who, through a mining mishap, burrow into the subterranean world of Pellucidar, 500 miles below the Earth's surface. Pellucidar is inhabited by prehistoric creatures of all geological eras, and dominated by the Mahars, a species of flying reptile both intelligent and civilized, but which enslaves and preys on the local stone-age humans.