RIO, Antonio del (fee'-o), Spanish soldier, born in La Mancha in 1745 ; died in Guatemala about, 1789. He came in 1775 to this country as a captain, and was serving in Central America when, in 1786, the king of Spain appointed him commander of an expedition to make an examination of whatever ruins might be found in the territory of Guatemala, in order to settle the question, which was then greatly discussed, of whence America derived its inhabitants. Rio undertook his task in the same year with great zeal, and found the ruins of an ancient city near Palenque, in the present state of Chiapas, Mexico, the splendor of which suggested to him the idea that it was built by the first Phoenician adventurers that are thought by some to have sailed across the Atlantic ocean. Rio died shortly after his return to Guatemala, but left a manuscript about his explorations, which some years afterward fell into the hands of Dr. Pablo Felix Cabrera, who translated it into English and published it under the title of " Description of the Ruins of an Ancient City discovered near Palenque, in the Kingdom of Guatemala" (London, 1794). The volume also contains an investigation into the history of the American races, by Cabrera.