_Acalianes_. _Cacas_ or _Cacanas_. _Calchaquis_. _Catamarcas_. _Diagitas_ or _Drachitas_. _Quilmes_. _Tamanos_. The learned Barcena also prepared a grammar of the Natixana or Mogana language, spoken by the _Naticas_, whom we find mentioned by later authorities as neighbors of the Calchaquis in the government of Santa Fé.[526] They apparently belonged among the Chaco tribes. Barcena adds that nine different tongues were spoken in the district of Cordova, among which were the Sanavirona and Indama, which had not been learned by the missionaries.[527] _2. The Pampeans and Araucanians._ South of the Gran Chaco, say from south latitude 35°, begins the true Pampas formation. This, according to the geologist Burmeister, is not a marine deposit, but the result of fluvial overflows and dust storms. It is diluvial and quaternary, and overlies the Patagonian formation, which is marine and early Pleistocene. The pampas are in parts wide grassy plains, like the prairies of the upper Mississippi valley; in parts they are salt deserts, in parts more or less wooded. With little variety, this scenery reaches from the Chaco to the Rio Negro, S. lat. 40°. Nearly the whole of this territory was occupied by one linguistic stock. It is the same which is found in Chili, where its most prominent members are the Araucanians. Which was the course of migration, whether from the Pacific coast to the Pampean plains or the reverse, is not positively decided, but I am inclined to believe it was the latter. The ancestors of the Araucanians would not willingly have crossed the barren wastes of the desert of Atacama; there are evidences of a different people inhabiting Chili before they possessed it, and we have traces that they had not obtained full possession of that country at its discovery. This view does not deny subsequent migrations of the Araucanians into the Pampas under the pressure of the Spanish invasion.[528] In such moving they were simply returning to the traditional homes of their ancestors. As the name of the whole stock, I adopt the word Aucanian, from the Araucanian verb _aucani_, to be wild, indomitable, from which are derived the tribal names Aucanos and Aucas, occurring on both sides of the Andes.[529]