It being believed in Spain, before the fact was ascertained, that Ayolas was dead, the post of _Adelantado_ of _La Plata_ was conferred upon _Don_ Alvar Cabeza de Vaca, who had passed ten years as a prisoner amongst the natives of _Florida_. Cabeza de Vaca sailed from Spain with four hundred followers in the year 1540, and by the following March had disembarked at _Santa Catalina_, an island on the coast of _Brazil_, opposite _Paraguay_, where confirmation reached him of the death of Ayolas. He thereupon boldly proceeded from a point of the shore near to _Santa Catalina_, making direct by land for _Asuncion_. He took with him two hundred and fifty men with twenty-six horses, sending the remainder by water to _Buenos Ayres_. During nineteen days Cabeza marched through woods ere reaching a settlement of _Guaranís_, from whom he was enabled to obtain abundance of food for his men. Whilst resting with these friendly people, the explorer had the good fortune to fall in with a native on his way from _Asuncion_ to _Brazil_, and who undertook to retrace his steps and guide him to his seat of government. Leaving a region where a certain degree of civilisation existed--where maize and mandioc were cultivated, and where men lived in houses and reared fowls and ducks--the Spanish leader had once more to trust himself and his men to the toils and risks of a march through the primeval forest, through which, after having surmounted innumerable difficulties, they at length approached their destination. In the course of one day they had to construct as many as eighteen bridges for the passage of their horses. This march had mainly lain along the course of the river _Yguazû_, a tributary of the _Paraná_, which takes its rise near the Atlantic Ocean. In order to avoid a tribe which was reported to be hostile, Cabeza de Vaca embarked with part of his force on canoes, intending to proceed thus to the _Paraná_, whilst the rest of his men should march along the river’s bank to the point of junction of the two streams. But there was an obstacle in his way which prevented the execution of this scheme. The _Yguazû_, which stream is about one mile in breadth, while it flows through the Brazilian forest, suddenly becomes contracted, at a short distance above its junction with the _Paraná_, to the breadth of rather less than a thousand yards. It then breaks into several channels and rushes over a series of descents, the highest of which is one hundred and seventy-two feet. Of this cataract--which, though little visited, is perhaps the grandest in South America--the vicinity is made known by the roar of waters and by the rising of a mist which overspreads the falls to a height of more than one hundred feet.