The country between the Guapay and Ichilo is probably as little known as any part of South America. This strip of land, covering approximately five thousand square miles, is heavily forested, and is the home of a tribe of savages known as the Sirionós. Judging from the accounts given to us by our canoemen and the priest, they must be a terrible and indomitable race. The Yuracarés fear them greatly, and as we neared the Ichilo they preferred to keep the canoes in the centre of the river and seemed reluctant to land; if they shot at an animal and the arrow missed its mark and dropped in the forest they did not go in search of it; a half-day of careful work is needed to make an arrow, and as a general rule Indians are very particular to hunt for any they may lose; but in this instance they preferred the loss of the arrows to risking their skins in the dense cover. There were four Yuracarés at the mission, one, a girl of twelve years, who bore unsightly scars--the result of having been ambushed by parties of the Sirionós tribe; I was also told that occasionally some of them are killed. The Sirionós seem to have no permanent homes and cultivate the ground to a very limited extent, if at all. They are a tribe of wanderers, and roam the forest in small parties, killing game for food. In appearance and stature they are not unlike the Guarayos, but in temperament they are totally different and have successfully resisted every attempt made to subdue them. Their weapons are bows and arrows, the former of great height and so powerful that they cannot be drawn with the arms alone. In order to shoot the Indian throws himself on his back, grasps the bow with the feet and draws the cord with both hands; the arrows, of which the priest had collected a number, are seven or eight feet long and made of wild cane or _chuchilla_. Apparently they are unacquainted with the use of poison. Probably the Guarayos suffer more at the hands of the Sirionós than the Yuracarés, because the former two tribes come in contact more frequently. Padre Wolfgang, in charge of one of the missions of Santa Cruz de la Sierra, was on one occasion attacked and several of his men were captured. A few days later he found them nailed to trees with numerous long thorns. On another occasion he surprised a party of Sirionós and succeeded in capturing seven; these he took back to the mission, but they proved to be intractable. He found it necessary to tie them to posts in order to prevent them from escaping. They steadily refused food and water, and after a few days four died of starvation and sullenness. The priest took pity on the remaining three and released them.