Plesiosaurus

Plesiosaurus is the gigantic, shell-backed marine reptile that appears beside the expedition’s raft in the subterranean sea and battles the Ichthyosaurus. The encounter makes a prehistoric creature at once an object of scientific recognition and an imminent physical danger: its towering neck and combat with its rival send water over the raft, while its death leaves the travelers uncertain whether the surviving Ichthyosaurus will attack them next.

Identification and Appearance

At first the travelers cannot make sense of the creatures surrounding them. Hans tries to steer the raft away from danger, only to find a large turtle and a long serpent with an enormous head on the other side. The apparent choice between threats closes around the raft; the reptiles circle it while the travelers see no safe direction in which to flee.

The Professor identifies the serpent-like creature as the Plesiosaurus, the Ichthyosaurus’s formidable rival. Its shape combines a cylindrical trunk and a short, thick tail with a body covered by a carapace. A bank of fin-like limbs suggests oars, while a swanlike neck, flexible and more than thirty feet high above the waves, gives the animal a strikingly different profile from its shelled body. The narrator’s image of a tower of living flesh conveys the scale that makes its anatomy both marvelous and terrifying.

The recognition also corrects the travelers’ first impression of the scene. Hans is right that only two of the monsters disturb the sea’s surface: the apparent turtle and serpent are not separate animals, but the Plesiosaurus and its opponent. Naming the creature resolves the immediate confusion without making the encounter any safer. Scientific identification clarifies what the travelers are seeing; it does not put them beyond its reach.

The Raft in the Monsters’ Path

The two reptiles’ appearance turns observation into a crisis. Their enormous size makes the raft seem almost helpless: earlier in the encounter, the narrator estimates that even the smallest of the monsters could crush the travelers’ vessel with a single bite. Once the reptiles advance and twist around it, the travelers take up their rifles, though they doubt bullets can pierce the creatures’ armor-like scales or frighten them away.

The Plesiosaurus is not simply an animal observed at a distance. Its rival’s approach leaves Hans steering hard to escape one danger, only to find the shelled reptile and its long neck to leeward. The travelers cannot maneuver out of the closing circle. For a time the surrounding monsters intensify the impression of entrapment; most eventually dive beneath the waves, leaving the two principal reptiles to dominate the surface and the raft’s immediate peril.

As the Plesiosaurus and Ichthyosaurus attack, their struggle raises mountains of water that break over the raft and toss it about. The narrator cannot reliably distinguish one combatant from the other as they grapple, and their hissing seems to reverberate through the cavern’s granite roof. The fight is therefore both spectacle and hazard: the travelers are witnesses to a previously unseen contest, but the force of that contest repeatedly threatens to overturn their fragile vessel.

Battle with the Ichthyosaurus

The combat continues for one, two, then three hours without a decisive result. The reptiles draw away from the raft and return toward it; each apparent chance that they have left the travelers alone gives way to a renewed approach. The travelers crouch ready to fire, resolved not to perish without resistance even though their weapons appear unlikely to injure or deter the combatants.

The long, unresolved struggle makes the raft’s danger depend on a contest whose outcome the travelers cannot control. The animals hold one another in a close embrace, and the narrator cannot tell which has the advantage. When both disappear from sight for several minutes, the witnesses do not know whether the combat has ended beneath the surface or whether its final act is simply hidden from them. The pause offers no assurance of safety.

The Plesiosaurus then rises nearby, wounded unto death. The narrator can see little of its great body, only its serpentine neck twisting through its final convulsions. It lashes the water like a gigantic whip, then writhes in the manner of a severed worm; spray sweeps across the raft and nearly blinds the travelers. Its movements visibly slacken before its body settles as an inert mass upon the surface of the calm sea.

Death and Narrative Significance

The Plesiosaurus’s death resolves the battle’s immediate uncertainty, but not the expedition’s danger. The Ichthyosaurus’s fate remains unknown: it may have returned to the cavern beneath the sea, or it may reappear and attack. The travelers therefore gain a brief breathing space rather than a secure escape. The dead animal is a consequence of the contest, while the surviving rival preserves its threat beyond the scene’s apparent conclusion.

The episode gives the Plesiosaurus a double narrative role. Its distinctive anatomy enables recognition of a creature from the primitive ocean, turning the travelers’ encounter into an extraordinary moment of observation. Yet the same body—the shell, the high flexible neck, the mass capable of churning the sea—resists being reduced to a specimen: it is an active force in a struggle that can capsize the raft. The scene moves from mistaken appearance to scientific naming, then from wonder to danger and finally to a death that still cannot guarantee safety. The creature’s defeat closes the duel, not the uncertainty surrounding the travelers.