listened anxiously for an answer from the ridge. The silence, however, continued.

"I believe it was a scout," said White Otter. "Perhaps he was calling his people."

"Perhaps we will hear the ponies," suggested Little Raven.

"We are too far off," White Otter told him. "Those people will ride easy."

"Perhaps it was only Ma-ya-sh," said Sun Bird. "Perhaps he went there to drink."

"Yes, it may be true, but I believe it was some one different," replied White Otter. "We are in the country of our enemies. We must be sharp."

CHAPTER II

MYSTERIOUS SIGNALS

Fearful that a company of foes might have taken shelter in the little grove of cottonwoods, the Sioux determined to take every precaution against a sudden attack. While Little Raven remained in the ravine with the ponies, White Otter and Sun Bird seated themselves upon the plain to listen for sounds from the grove. All was still. They began to wonder if they had been needlessly alarmed. At that moment one of the ponies whinnied softly. White Otter and Sun Bird scrambled wildly into the gully. Little Raven had already seized the pony and turned its head out of the wind. The other ponies also seemed restless and nervous, and White Otter and Sun Bird attempted to quiet them.

"It is bad," White Otter said, softly. "I believe some one is riding this way."

The thought was startling. The Sioux stood beside their ponies, listening uneasily. One question flashed through the mind of each of them. Were enemies approaching stealthily under cover of the darkness? They heard nothing to give them a clew. Many moments passed. The silence increased their suspense. They believed they were in peril. It seemed folly to loiter in the ravine.

"Come, we will go," whispered White Otter.

They mounted the ponies and rode from the ravine. Once on the plain, they stopped for a moment to listen. Then the pony again attempted to call, but Little Raven silenced it with his riding quirt. The warning was significant. The Sioux believed that strange horses were close at hand. They turned their ponies and rode silently away into the night. It was some time before they ventured to speak.

"Well, my brothers, I believe Ma-ya-sh came to find us," White Otter laughed, softly, when they were beyond earshot of the ravine.

"Yes, White Otter, I believe your words were true; I believe scouts were peeping over that ridge," Sun Bird told him.

"Do you believe they saw us?" Little Raven asked, anxiously.

"No," replied White Otter. "Perhaps they found out about our ponies."

Although they realized that it might be perilous to linger in the vicinity, the Sioux determined to remain within sight of the grove until they learned if their suspicions were real. When they reached a low ridge, a considerable distance to the eastward, they decided to stop and wait for daylight.

"See, pretty soon it will be light," said Sun Bird. "Then we will find out if there is any one over there in that place."

When the night shadows finally lifted from the plain, White Otter and Sun Bird concealed themselves below the crest of the ridge to watch, while Little Raven waited at the base of the slope with the ponies. The grove was in plain sight, and the Sioux watched expectantly.

"If there are hunters over there, pretty soon they will ride out to look for buffaloes," said Sun Bird.

"Perhaps they are watching," White Otter reminded him.

A few moments later they saw two horsemen ride from the grove, and turn toward the ravine. They rode across the plain at an easy canter, and showed little caution. As they drew near the ravine, however, they became more careful. Once within arrow range, they stopped, and it was apparent that they were watching the top of the gully. Then they rode slowly forward.

"Those are the scouts that peeped over that hill," declared White Otter. "I believe they are trying to find out about us."

The horsemen had disappeared into the ravine. The Sioux had been unable to identify them. They felt certain that the strangers would soon find the pony tracks. The idea alarmed them.

"Perhaps they will follow us," suggested Sun Bird.

"Watch," said White Otter.

The horsemen had suddenly appeared. They had crossed the ravine, and were riding slowly over the plain. The Sioux knew at once that they were looking for pony tracks. It was not long before they found them. They followed the trail a bowshot or more, and then they stopped. They were looking directly toward the ridge. The Sioux watched them in breathless suspense. They were straining their eyes to identify them, but the distance made it impossible.

"I cannot tell who they are," declared White Otter. "Can you tell about it?"

"No; they are too far away," Sun Bird told him. "Perhaps they will come closer."

"I believe they are talking about it," said White Otter.

At that moment the horsemen turned their ponies, and galloped off toward the west. They crossed the ravine, and rode toward the grove. They passed it, however, and continued toward the ridge farther to the westward. It was not long before, they disappeared.

"It is bad," declared White Otter. "Now we do not know who they are."

"Well, we know that our enemies are in this place," Sun Bird told him. "Now it will be useless to look for the buffaloes. If Ta-tan-ka comes, those scouts will tell their people about it. Yes, I believe they are looking for buffaloes."

"My brother, I feel different about it," said White Otter. "Perhaps those scouts are with a war party. Perhaps they are Pawnees. Perhaps they are going to fight my people. I must find out about it."

Sun Bird remained silent. It was not the part of a warrior to ask questions. He waited for White Otter to explain his plans.

"Now I will tell you what I propose to do," White Otter told him. "We must stay here and watch. Perhaps those scouts are trying to fool us. Perhaps they are trying to make us believe they have gone away. I believe they are peeping over that hill."

"Well, they will not catch us," laughed Sun Bird.

While White Otter continued to watch, Sun Bird crept down the slope to tell Little Raven about the two mysterious horsemen. The ridge to the westward was far away, and White Otter knew that it would be impossible to discover any one who might be hiding there. He had little doubt that at least one of the unknown riders had stopped to watch the plain.

"Did you see anything?" Sun Bird inquired anxiously, when he returned.

"No, I did not see anything, but I believe some one is watching over there on that hill," White Otter told him.

"Then we must be cautious," said Sun Bird.

They watched until the day was half gone, and then, having seen nothing to indicate that foes were loitering in the vicinity, they began to feel somewhat reassured. They wondered if the two horsemen might not have been stray hunters who had been led to the grove by the antelopes. Having found the fresh pony tracks, they might have feared to loiter in the locality. In spite of the possibility, however, the Sioux resolved to take no chances.

"We will keep watching," declared White Otter.

Soon afterward their patience was rewarded when they saw what appeared to be a cloud of dust or smoke rising behind the distant ridge. They watched it with great interest. For some time it puzzled them. It was faint and indistinct, and they wondered if it was dust raised by the hoofs of buffaloes or ponies. Then they noted that it seemed to rise