This picture of a tortoise might be what the crew of the Mitchell saw when they stopped in the “Mystic Isles” (Galapagos Islands) to stock up on Tortoises. These creatures provided meat and water during a long voyage west along the equator. They could be kept alive for months in the hold of the ship.
Melville: “These mystic creatures, suddenly translated by night from unutterable solitudes to our peopled deck, affected me in a manner not easy to unfold. They seemed newly crawled forth from beneath the foundations of the world. Yea, they seemed the identical tortoises whereupon the Hindu plants his total sphere […] The great feeling inspired by these creatures was that of age: datelessness, indefinite endurance. And in fact that any other creature can live and breathe as long as the tortoise of the Encantadas, I will not readily believe. Not to hint of their known capacity of sustaining life while going without food for an entire year, consider that impregnable armor of their living mail. What other bodily being possesses such a citadel wherein to resist the assaults of Time? […] With them I lost myself in volcanic mazes, brushed away endless boughs of rotting thicket, till finally in a dream I found myself sitting cross-legged upon the foremost, a Brahmin similarly mounted upon either side, forming a tripod of foreheads which upheld the universal cope. Such was the wild nightmare begot by my first impression of the Encantadas tortoise. But next evening, strange to say, I sat down with my shipmates and made a merry repast from tortoise steaks and tortoise stews” (Melville 1967 [1854]).