“What on earth’s the matter with him?” exclaimed Don, as he urged the camel forward.

But the beasts refused to move a step, and now Don discovered that the animal was trembling.

He looked about to see the reason. Suddenly, he discovered in the sand a few feet ahead a horrid swaying head with what seemed to be horns and a pair of fierce, wicked eyes that glowed like fire.

At first he could see no body. The creature seemed to be all head. But as Don looked more closely, he could see a shape of light brownish color with yellow spots, partly hidden in the sand. The eyes were glowing like those of a basilisk, and the body began to coil as though for a spring.

Quick as thought, Don reached for his rifle, took swift aim and fired. The bullet smashed the head of the creature, and the sand went up in clouds, as the body thrashed about furiously.

“Good shooting!” cried Teddy admiringly, as they dismounted to examine the reptile.

“What’s the shooting about?” asked the captain, as he came riding up with the rest of the party.

“This,” answered Don, as he prodded the snake with the muzzle of his rifle.

“A cerastes!” exclaimed the captain, who recognized it at once. “It’s one of the deadliest snakes in the world. If you were bitten by that, you’d be dead in half an hour.”

“Cleopatra’s asp,” pronounced the professor. “It was one of those with which the Egyptian Queen committed suicide.”