7th. RIO DE TOLOTLAN, RIO GRANDE DE SANTIAGO. This is one of the longest and most important of Mexican rivers, formed by the junction of the LAXA and LERMA, near Salamanca, in the state of Guanajuato, and falls into the Pacific near San Blas after a course of about two hundred leagues. The Rio Bayóna or Cañas is an important stream on the coast near the boundary between Jalisco and Sinaloa. 8th. The RIO DE CULIACAN rises in the north of the state of Durango, where it is called RIO SANZEDA, thence it takes its course towards the north-west, receiving some smaller streams, and then passing by the town of Culiacan, falls into the Gulf of California. The RIO DE ROSARIO, RIO DE MAZATLAN, debouche in the same gulf. The rivers PIASTLA, ELOTA, TAVALA, EMAYA, MOCORITO, SINALOA or OCRONI, AHOME, are small streams on the coast of Sinaloa. 9th. The RIO DEL FUERTE has its source in the metalliferous mountains of Batopilas and Uruachi, in the state of Chihuahua, where it is known as the river BATOPILAS. It takes a westerly course across the state of Sinaloa about 27° north;--it receives a number of other streams, on the western slope of a range of the Cordilleras, and finally flows into the California Gulf. 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.