Ichthyosaurus

Ichthyosaurus is a giant marine reptile that the explorers encounter alive in the subterranean sea, where it fights Plesiosaurus beside their raft. Professor Hardwigg identifies it by its hybrid-looking features, and the ensuing combat turns a scientific observation into an immediate survival crisis: the two animals churn the water around the fragile vessel, while the explorers can only watch and hope not to be overturned. Plesiosaurus dies, but Ichthyosaurus vanishes beneath the waves, leaving its fate—and the explorers’ safety—uncertain.

Recognition and Appearance

At first, the creature is perceived through fragments of alarming spectacle: immense fins, water thrown high above the sea, and a body powerful enough to crush the raft. The explorers initially misread its appearance. Professor Hardwigg explains that its snout resembles a porpoise’s, its head a lizard’s, and its teeth a crocodile’s; this combination, rather than any single feature, has caused the confusion. He identifies the animal as Ichthyosaurus, the great fish lizard and one of the formidable reptiles of the ancient world.

The narrator’s closer account gives the identification physical scale. Ichthyosaurus has flaming red eyes, each as large as or larger than a man’s head, and is estimated at no less than a hundred feet long. Its enormous tail rises above the water, while the size and strength of its jaw suggest a formidable bite. The narrator reports that naturalists counted at least 182 teeth. The creature’s imposing anatomy makes the explorers’ first impression of overwhelming danger seem entirely justified.

Its eyes are described not only for their size but for their apparent adaptation to the deep sea. The narrator attributes to them exceptional power, capable of withstanding the pressure of the heavy water layers in the depths where the animal usually feeds. This account combines a startling encounter with the period’s explanatory language: the creature is presented as a living survivor of an ancient marine world, its body legible to the observer through both immediate sensation and geological knowledge.

The Battle with Plesiosaurus

The encounter takes place while the explorers are aboard their raft on the underground sea. As they try to escape the surrounding monsters, Hans seizes the rudder and steers away, only to find danger on the other side as well. The raft is hemmed in by enormous reptiles; the creatures wheel around it in concentric circles, and the explorers cannot choose a direction that promises safety. Their weapons offer little reassurance against the armor-like scales of the animals around them.

Professor Hardwigg watches the apparent duel with a telescope and identifies its participants. The other combatant is Plesiosaurus, which he describes as a serpent-like sea reptile concealed beneath a hard shell. The two creatures alone disturb the surface of the sea. Their fight is not a distant natural-history spectacle: it raises mountains of water that wash over the raft, and the vessel is repeatedly close to capsizing. The explorers crouch ready to fire, despite recognizing that rifle shots are unlikely to injure or frighten the monsters.

The struggle lasts for hours without a decisive result. The reptiles alternately draw away from and approach the raft, bringing their deadly contest repeatedly back into the explorers’ immediate vicinity. Their close embrace makes it difficult to distinguish one animal from the other. The narrator experiences the scene as dreamlike, yet the danger is concrete: whichever creature prevails may turn its attention to the small vessel nearby.

Both reptiles suddenly disappear beneath the waves, leaving a maelstrom that nearly draws the raft down. After several minutes, Plesiosaurus resurfaces, mortally wounded. Its long neck lashes and twists in its death throes, sending water across the raft; then its movements weaken until its body lies dead on the calm surface. The sequence confirms Plesiosaurus’s death but does not resolve Ichthyosaurus’s fate. The narrator cannot tell whether the surviving animal has retreated to its cavern beneath the sea or will return to destroy the explorers. Its disappearance gives them only temporary breathing space.

Fossils, Geological Time, and the Living Past

Elsewhere in the underground passage, the explorers’ progress through rock makes geological time visible in successive strata and fossil remains. They move into what the narrator calls a transitional state among Silurian rocks; later, he observes remains of a more developed animal order than the rudimentary trilobites he had previously seen. He interprets this sequence as an ascent through animal life. These observations frame the underground world as a record of deep time, but the sea encounter radically changes the scale and immediacy of that record: the ancient animals are not simply imprinted in stone but moving and fighting before the expedition.

That reversal resonates with the nineteenth-century debate about how far back human existence reached. The account recalls the 1863 discovery of a human jawbone fourteen feet beneath the soil at Moulin-Quignon, near Abbeville, and the controversy over whether the find established that humans lived during the Quaternary. Professor Hardwigg supported the jawbone’s authenticity alongside many geologists, while Elie de Beaumont argued that the deposit was less ancient. Subsequent reported finds and evidence of human workmanship in much older deposits intensified arguments about humanity’s antiquity. The novel’s movement from disputed fossils and geological interpretation to a witnessed living Ichthyosaurus turns that period’s fascination with remote time into adventure, while keeping the distinction between contemporary scientific claims and the explorers’ extraordinary fictional experience.

Narrative Significance

Ichthyosaurus is at once an object of recognition and an active threat. Professor Hardwigg’s classification gives the encounter the precision of a scientific demonstration, but that composure contrasts with the explorers’ helpless position on the raft. Naming the animal does not tame it: knowledge identifies the danger and describes its anatomy, yet offers no reliable means of protection from its strength.

The episode also transforms the expedition’s relation to the prehistoric past. Fossils had allowed the travelers to infer successive forms of ancient life from traces in rock; the living reptile makes that history present, immense, and perilous. The fight supplies no uncomplicated triumph of human understanding. Plesiosaurus dies, but Ichthyosaurus remains unaccounted for, so the explorers’ brief relief is shadowed by the possibility that the survivor may return. Its unresolved disappearance carries the encounter’s tension beyond the battle itself.