"By Gad, that's right! The tulalaroo bird. Doesn't mind heat or cold, either one. Nests in ice or red-hot coals! That's rather interesting, Doctor. Any more such examples?"
"Scores! There is the fabled unicorn ... a one-horned gazelle-like animal certainly not indigenous to Terra, yet it found its place in the 'unnatural natural history' of not one but a dozen races. Whence originated this record of a single horned creature we could not guess .. until we discovered such a beast on Venus.
"The fabulous 'salamander' turned out to be a common asbestos-like lizard of Mercury. Aqueous Venus solved for us the problems of the mermaid, the sea serpent and the undine. On mighty Jupiter mythologists encountered the fire-breathing saurian which gave rise to the 'dragon' myth—"
"But, Doctor Roswell!" gasped the girl, "what does this mean? That once upon a time, countless centuries ago, beasts of this sort roamed Earth? Or—?"
Rocky shook his head soberly.
"We do not know, Miss Graham. There are a number of equally valid possibilities. One is that which you have mentioned ... that Earth was once host to all the types of animal life now to be found on its sister planets. Another is that aeons ago Earthmen—or the intellectual rulers of one of the other planets—knew the secret of spacetravel. The factual records of places visited, strange sights seen, would in the musty passage of time become mythology.
"Still another possibility—"
"Yes?"
"Well, it is ... er ... a theory recently advanced by an erudite scholar, but it has elements of fantasy which make it almost incredible. You are ... er ... familiar with the theories of Svante Arrhenius?"
Lynn frowned. "I remember the name faintly. Didn't he claim life traveled through the ether?"