He pointed to the motionless figures in the cages as, one by one, they passed them. "A cow," he said, "which I brought through from the Fiftieth Century. Notice the exaggerated udders. The result of centuries of cross-breeding for milk. Somewhat different from the same beast of your day, I presume. "This next is a pterodactyl from the Jurassic Age. I am glad to say it lived two whole weeks after coming down through the warp. The hardier animals were the only ones to survive at all--until I perfected my process. You have already seen my brontosaurus. A harmless thing. We allow it to roam freely, but we had to destroy the dinosaur that came after it.... "You recognize this sabre-toothed tiger? And the kangaroo? An interesting subject, by the way. I brought it through from the year 12,000. It had reached a high stage of development and could converse in simple phrases. A far cry from man's estate, however." "You mean," said Sandra, "it could talk?" "Oh, yes. But then many of the lower animals _do_ speak, you know. Of course I use the ancient meaning of the word. I mean they employ the vocal organs. They have not _this_!" He tapped the skull covering which both Larry and the girl had noticed before. "That?" said Larry wonderingly. "What is it?" But the little man was wringing his hands in exasperation. "Now, I declare!" he cried. "All this time, you have been opening and closing your mouths while we were communicating, and I thought it was caused by some physical disturbance! _You_ use vocal converse, too!" "But of course," said the girl. "It is quite unnecessary!" snapped the scientist. "With the _menaudo_, I can understand your thoughts clearly--and communicate my own to you, as well. In the future, both of you will be kind enough to think without speaking!" "Why?" asked Larry bluntly. "Miss Day and I aren't mind-reading big-brains like you. If we wish to speak to each other--" For the first time since they had met him, Harg's ever-present smile faded. A trace of his annoying superiority, self-confidence, seeped away. In his eyes there was a groping expression oddly akin to fear. "There is nothing you need tell her!" he ordered. "I do not care to risk my--" He stopped suddenly, cannily. When he spoke again, it was in a milder tone. "You may, if you wish, converse with your mouths when I am not present. But in my presence I require you to think your conversation." A sudden suspicion began to form in Larry's mind. He stifled it instantly; thrust it from him lest Harg grasp that faint, half-formed thought. Hastily he changed the subject. "This other beast--" he began aloud. Then, remembering Harg's warning, he stopped and rephrased the query in his mind. "This other strange beast," he thought. "What is it?" He knew, then, why Harg had taunted him for his interest in the mechanism of the door. For swift as an arrow the answer formed itself in his brain.