In the wide valley between the Eastern and Central Cordilleras, and taking the drainage of the whole watershed is the River Agusan. Rising about the 7th parallel on the slopes of Mt. Tagoppo, this river runs a very sinuous course in a general northerly direction, but inclining slightly to the west, receiving innumerable tributaries on either side. At about 8° 15' N. Lat. the Agusan expands or overflows, forming a series of shallow lakes, choked up with driftwood and vegetation, and varying in extent with the rainfall. Continually gathering volume, it runs into the Bay of Butuan about 9° N. Lat. At Moncayo, in 7° 45' N. Lat., the Agusan is one hundred yards wide, and is navigable for canoes even much higher up. The spur previously spoken of as striking east and south from Mt. Panamoyan, forms two small watersheds. The western one gives rise to the River Libaganon, and the eastern to the River Salug. Both these rivers run in a southerly direction, and unite to form the River Tagum, which runs for a short distance S.E. and falls into the head of the Gulf of Davao. A little way south of Mt. Panamoyan some mountain streams dash down the sides of the Cordillera and running through a gap unite to form the River Davao which flows in a south-easterly direction till it reaches the plain, when it changes its course and runs east into the Gulf of Davao. From Point Sipaca, in 9° N. Lat., a range of mountains stretches in a southerly direction for about sixty miles. Amongst these are Mt. Sipaca, Mt. Saorag, and Mt. Quimanquil. With the Central Cordillera this range forms a watershed, and the torrents on the steep sides of Sinalagao and Quimanquil dash down and take a southerly direction to form the headwaters of the River Pulangui and ultimately become the Rio Grande. In 7° 50' N. Lat. two important affluents join, the River Sauaga and the River Malupati, a few miles lower the Calibatojan and the Kaya-Kaya bring their tribute, and the united flood with rapid current casts itself headlong into the deep Cañon of Locosocan and runs in this for over four miles to Salagalpon, where another cataract occurs. The river continues for miles a rushing torrent amongst huge boulders, at the bottom of this cleft, so narrow in places, where the rocks jut out and nearly meet overhead, that it seems like a tunnel. In 7° 46' N. Lat. there is a small volcano close to the left bank which, whenever it rains, becomes active and gives off stifling fumes of sulphur. At Mantanil, in 7° 40' N., the river can be navigated on bamboo rafts, handled by skilled Manobo pilots, but not without much risk; for some distance down there are two buchis, or sinks, where the water runs down into subterraneous passages through the river-bed, forming dangerous whirlpools. There are also several rapids which require great dexterity to pass safely. The banks are still high; but, on approaching the confluence of the Kulaman river, on the left bank, the gorge is much lower, and on arriving at Ilang