This voracious animal, called by naturalists the _Canis jubatus_, is in shape like a large dog, and has the head of a fox. Its fur is a reddish-cinnamon color, and there is a black mane all down the back. It is a strong, nimble animal, generally inhabiting marshy places, and pursuing aquatic animals by swimming, prowling about by night and sleeping during the day. Its attacks are particularly dreaded at the ESTANCIAS, or sheep stations, as it often commits considerable ravages, carrying off the finest of the flock. Singly, the AGUARA is not much to be feared; but they generally go in immense packs, and one had better have to deal with a jaguar or cougar than with them.

Both from the noise of the howling and the multitude of shadows leaping about, Glenarvan had a pretty good idea of the number of the wolves, and he knew they had scented a good meal of human flesh or horse flesh, and none of them would go back to their dens without a share. It was certainly a very alarming situation to be in.

The assailants were gradually drawing closer. The horses displayed signs of the liveliest terror, with the exception of Thaouka, who stamped his foot, and tried to break loose and get out. His master could only calm him by keeping up a low, continuous whistle.

Glenarvan and Robert had posted themselves so as to defend the opening of the RAMADA. They were just going to fire into the nearest ranks of the wolves when Thalcave lowered their weapons.

"What does Thalcave mean?" asked Robert.

"He forbids our firing."

"And why?"

"Perhaps he thinks it is not the right time."

But this was not the Indian's reason, and so Glenarvan saw when he lifted the powder-flask, showed him it was nearly empty.

"What's wrong?" asked Robert.

"We must husband our ammunition," was the reply. "To-day's shooting has cost us dear, and we are short of powder and shot. We can't fire more than twenty times."

The boy made no reply, and Glenarvan asked him if he was frightened.

"No, my Lord," he said.

"That's right," returned Glenarvan.

A fresh report resounded that instant. Thalcave had made short work of one assailant more audacious than the rest, and the infuriated pack had retreated to within a hundred steps of the inclosure.

On a sign from the Indian Glenarvan took his place, while Thalcave went back into the inclosure and gathered up all the dried grass and ALFAFARES, and, indeed, all the combustibles he could rake together, and made a pile of them at the entrance. Into this he flung one of the still-glowing embers, and soon the bright flames shot up into the dark night. Glenarvan could now get a good glimpse of his antagonists, and saw that it was impossible to exaggerate their numbers or their fury. The barrier of fire just raised by Thalcave had redoubled their anger, though it had cut off their approach. Several of them, however, urged on by the hindmost ranks, pushed forward into the very flames, and burned their paws for their pains.

From time to time another shot had to be fired, notwithstanding the fire, to keep off the howling pack, and in the course of an hour fifteen dead animals lay stretched on the prairie.

The situation of the besieged was, relatively speaking, less dangerous now. As long as the powder lasted and the barrier of fire burned on, there was no fear of being overmastered. But what was to be done afterward, when both means of defense failed at once?

Glenarvan's heart swelled as he looked at Robert. He forgot himself in thinking of this poor child, as he saw him showing a courage so far above his years. Robert was pale, but he kept his gun steady, and stood with firm foot ready to meet the attacks of the infuriated wolves.

However, after Glenarvan had calmly surveyed the actual state of affairs, he determined to bring things to a crisis.

"In an hour's time," he said, "we shall neither have powder nor fire. It will never do to wait till then before we settle what to do."

Accordingly, he went up to Thalcave, and tried to