The cry of an alligator which was raised in the silence warned them that they were to halt. Two minutes later the same cry raised twice caused them to throw themselves in the saddle, and then at last, at the cry of the owl, they darted off at a gallop, doubled in pace by the instinctive fear that they experienced of terrible danger. The marquis had ordered doña Laura to mount on horseback. The young girl obeyed passively, without uttering a word, and had placed herself, as well as her slave, in the middle of the line of horsemen. The marquis had wished this because this position appeared to him least dangerous. During all the night the Brazilians, leaning on the necks of their horses, galloped on. At sunrise they had made eighteen or nineteen leagues, which was enormous, but the poor horses were spent. At a league before them the fugitives perceived a broad stream. It was the Pilcomayo, one of the most considerable affluents of the Rio Paraguai. The marquis approached the captain. "We have done wonders, Diogo," said he to him; "thanks to your admirable arrangements, we are saved." "Do not thank me yet, my lord," answered the Indian, with a mocking smile "all is not yet finished." "Oho! We have now an advance of our enemies which puts us out of their reach." "We have gained no advance on the Guaycurus, my lord; our only chance of safety is to reach the river, and to cross it." "Well! What prevents us from doing so?" "Look at the horses; before we have got half the distance which separates us from the Pilcomayo, the enemy will be upon us." "You are thoroughly obstinate to the end; you see yourself that the plain is perfectly clear." "You think so, my lord?" "Why, I have looked in vain in every direction." "That is because you are not used to the prairie, that is all. Look," added he, stretching his arm in the direction of the northeast. "Notice that convulsive undulation of the high grass." "Just so; but what does that prove?" "Do you see again," continued the impassable captain, "those companies of nandus and of seriemas who run madly in all directions. Those flights of guaros and of kamichis?" "Yes, yes, I see all that; well?" "Well! Well, your Excellency, the undulation of the grass without apparent cause, since there is not a breath of air stirring, the mad course of the nandus and the seriemas, and the frightened flight of the guaros and the kamichis, simply mean that the Guaycurus are on our track." "But in an hour we shall have crossed the river." "With our horses that is impossible; it is with difficulty that they can put one foot before the other." "That is true," murmured the marquis, "but then what is to be done?" "Prepare ourselves to die." "Oh, that is not true that you say, Diogo." "In an hour not one of us will exist," coolly answered the captain. "But we shall not allow ourselves to be assassinated without defending ourselves?" "That is another question, my lord. Will you fight to the last gasp?"