He led Forrester across the cave until they came to a spot whence the floor shelved down steeply to the wall. That part of the wall which was below the general level of the floor was brightly luminous, and on its green surface Forrester saw, as on a screen, the shadowy forms of fishes and aquatic reptiles flitting hither and thither. Watching them curiously, he was astonished when, at one and the same moment, they dispersed with a rapidity betokening terror, some to the right, some to the left. For an instant the screen was left blank; then there appeared upon it a monstrous skeletonised form, somewhat resembling the fantastic creatures depicted on the walls of the Temple, and on the wall of his own cell. It combined in one shape all the most hideous features of the alligator, the rhinoceros, and the dog-fish immensely magnified. Involuntarily Forrester started back as the figure came close up to the wall, and seemed to be looking through it, as the fish in an aquarium look through the glass of their tank. But it was a shape only; its eyes could not be seen.
"What is it?" Forrester asked in a whisper.
"I don't know," his companion responded. "It is not one of any of the species of ichthyosaurus that I have ever seen; but it is liker that reptile than to any other known creature."
"But isn't that extinct? Don't they find merely the fossil remains of it?"
"Who is to say that any creature is extinct? Scarcely a year passes but some explorer finds, in some remote neglected region, what is to him a new type, but in reality, no doubt, dates back to an antiquity beyond computation. This hideous creature seems to be the last of his kind; I have seen no sign of a mate; and his extinction would not be much of a loss."
"How can we see him at all, through the wall--just as we saw you coming down here three days ago?"
"Does no explanation occur to you?"
"Well, of course I have heard of X-rays, and things of that kind; but----"
"Exactly. Excuse my interruption, but I know what you were going to say. You were going to speak of cathodes, and vacuum tubes, and phosphorescent screens, and----"
"I wasn't," said Forrester: "I never heard of them."