1918. The complete trilogy was later combined for publication in book form under the title of the first part by A. C. McClurg in June 1924. Beginning with the Ace Books editions of the 1960s, the three segments have usually been issued as separate short novels. Starting out as a harrowing wartime sea adventure, Burroughs's story ultimately develops into a lost world story reminiscent of such novels as Sir Arthur Conan Doyle's The Lost World (1912) and Jules Verne's The Mysterious Island (1874) and Journey to the Center of the Earth (1864). Burroughs adds his own twist by postulating a unique biological system for his lost world, in which the slow progress of evolution in the world outside is recapitulated as a matter of individual metamorphosis. This system is only hinted at in The Land That Time Forgot; presented as a mystery whose explication is gradually worked out over the cours