Right at the fork of the road and about fifteen feet from the automobile was the strange design. It was rudely cut out of stone, a serpent twining about a tree-trunk. There was nothing remarkable in the image itself except for the quaint, laughing expression the sculptor had managed to carve on the mouth of the reptile.
"I wonder how it came here?" asked Jerry, getting out of the car and going close for a better look.
"Probably a relic of the Aztec race," replied the professor. "They were artists in their way. This must be the image the old Mexican mentioned. If it is I suppose we may as well follow his advice and take the road to the left."
"The road to the buried city," put in Jerry. "We must be close to it now."
"Isn't that something sticking in the mouth of the image?" asked Bob.
"It looks like a paper," said Ned. "I'll climb up and see what it is."
He scrambled up the stone tree-trunk, about which the image of the laughing serpent was twined. Reaching up, he took from the mouth of the reptile a folded paper.
"It's written in some queer language; Spanish, I guess," replied Ned. "I can't read it."
"Bring it here," said Professor Snodgrass. "Perhaps I can make it out."
The naturalist puzzled over the writing a few minutes. Then he exclaimed:
"It's from our old friend, the Mexican magician. He tells us to turn to the left, which is the same advice he has given us before, and he adds that we must beware of some sudden happening."
"I wonder what he means by that?" asked Jerry.
"Probably nothing," answered the professor. "But if something does happen, and he meets us after it, he'll be sure to say he warned us. It's a way those pretended wonder-workers have."
"How do you suppose the note was placed there?" inquired Bob. "We left the Mexican many miles behind."
"They are wonderful runners," answered the naturalist. "The magician may not have placed it here himself, but he may have given it to a friend. Perhaps there was a relay of runners, such as used to exist among the ancient Mexicans to carry royal messages. The old Mexican, who, somehow or other, discovered our object in this country, probably wanted to impress us with his abilities in the mystifying line."
The travelers spent a few minutes examining the queer, carved serpent. There were no other evidences of the existence of man at hand, and, except for the two roads, there was nothing to be seen but an almost unbroken forest. It was a wild part of Mexico.