After an extensive course, the Arinos loses the name, upon incorporating with the Juruenna, the united waters forming the Tapajos, properly Tapayo, from a nation of this name, who inhabited its margins further to the northward. The first considerable river united with it by the right is the Azevedo, so denominated after its discoverer. At a great distance lower down is the embouchure of another river on the right, thirty fathoms in width. A little further two morros approximate, and contract its bed, and an elevated island divides it into two channels, through which its waters flow with equal rapidity. From hence about three hours’ voyage is a cascade of considerable altitude, the murmuring noise and evaporation arising from which announce another of the wonders of nature long before it becomes visible. Beyond this interesting object is discovered the mouth of another river, apparently at least equal to the Tapajos, which is here very wide; but is however almost immediately reduced by two lateral morros to a little more than one hundred fathoms of width, and after a short space again presents a more than ordinary expansion, and receives also by the right margin another river of thirty fathoms in width. It is about three hours’ navigation from the mouth of one river to the other. Upon the margin of the Rio Preto, at the place where the canoes commence their voyage, a povoaçoe is now establishing for the accommodation of the navigators of the Tapajos. _District of_ TAPPIRAQUIA. This comarca derives its name from one of its tribes of Indians, and is limited on the north by Xingutania, on the west by the river Xingu, which separates it from the preceding district, on the south by Bororonia, and on the east by the river Araguaya, which divides it from Nova Beira. It comprises the same length as the Arinos from north to south, and upwards of two hundred miles from east to west. With the exception of the eastern boundary, along the Araguaya, it is unknown, for want of the relations of those who penetrated into it at an earlier period. Amongst other nations who have this district under their dominion, are the _Guapindaias_; the _Tappiraques_, who afford it the name; the _Ximbiuas_, and the _Aracis_. The southern part contains various rivers. The most remarkable are the Boys, Barahu, Irahiras, and Xanacy, all arms of the great river Xingu, but it is not known which is its principal head. Those that originate more to the east form the river St. Joao, which enters the Araguaya above fifty miles north of the river Mortes. To the south of its embouchure there is a large lake which communicates with it, as well as with the river that receives it, during the periodical floods.