10th. The Rio Mayo is the boundary stream between the states of Sinaloa and Sonora; at its mouth in the Gulf of California is the small port of Santa Cruz de Mayo, or Guitivis.
11th. The Rio Hiaqui, or Yaqui, rises on the west slope of the Sierra Madre, near the village Matatiche in the state of Chihuahua, whence its course is west south-west, across the state of Sonora; it receives the Rio Grande de Bavispe which rises in the state of Chihuahua, and also the Rios Oposura and Chico, and, finally, is lost in the Gulf of California, at about 27° 37´ north latitude.
12th. Rio de Guayamas. This river rises at San José de Pimas, in latitude 28° 26´ north, its course is west south-west, and its mouth in the Californian Gulf, at the fine and favorite harbor of San-Jose de Guayamas in latitude 27° 40´.
13th. The Rio de la Ascension rises at about 31° 40´ north and 112° 37´ west longitude. On its south-westerly course it receives the tributary waters of the Rio de San Ignacio and falls at about 30° 20´ north into the Gulf of California.
14th. Rio de Colorado. This important