The breeze soon carried the scent of the pursuing party to the nostrils of the antelopes, too; but they did not notice Rhoda. She brought up her rifle, shook her pony's reins, and in half a minute stood up in her short stirrups and drew bead on the white spot behind the fore shoulder of one of the running antelopes.
The distance was almost the limit for that caliber of rifle; but the antelope turned a somersault and lay still, while its mates turned off at a tangent and tore away across the plain.
It was several minutes before Walter and the other girls rode up. Rhoda had not dismounted. She was not looking at the dead antelope. Instead, she had unslung her glasses again and was staring through them westward—toward the slate-colored cloud that was climbing steadily toward the zenith.
When the ponies were halted and the sound of their hoofs was stilled, the young people could hear a moaning noise that seemed to be approaching from the direction toward which they were facing at that moment—the west.
"Oh!" cried Nan, "what is that?"
"Have you seen it before?" demanded Rhoda, shutting the glasses and putting them in the case.
"Yes."
"I wish I had," Rhoda said. "Hurry up, Walter, and sling that antelope across your saddle. Look out that the pony doesn't get away from you. Maybe he won't like the smell of blood. Quick!"
"What is the matter?" cried Bess, while Grace began to flush and then pale, as she always did when she was startled.
"It is a storm coming," answered Rhoda shortly.