The Kayans of Dutch Borneo are not numerous. Outside of Long Blu on the Mahakam they are found chiefly on the Kayan River in the large district of the northeast called Bulungan. They occupy the lower course, reaching not quite to Long Pangian, though having settlements there. Three subtribes are known to exist here, Oma-Gaai, Oma-Laran, and Oma-Hiban. The first named, also called Segai, live in Kaburau, Bruen, and Long Pangian. They appear somewhat different from the rest in language, and they abstain from rusa (deer) as food, while the others eat it. They file off ten teeth in the upper front jaw. At the headwaters of the Kayan River in Apo Kayan lives a subtribe, Oma-Lakan, said to number about 400; these do not file the front teeth. In Chapter IX is described a recent head-hunting raid by the Kenyahs on these Kayans. KENYAHS The Kenyahs are found only within the Bulungan district on the Kayan River. They are settled principally at the headwaters in Apo Kayan and at the sources of a northern tributary, the Bahau, in Podjungan. In these two regions it is estimated that they number altogether about 25,000. Down the river they have a few kampongs below Long Pangian, in the same vicinity; west of it are a few more, as mentioned in the description of my journey. On attempting to ascend the river further one would soon reach a vast extent of country entirely uninhabited except around the headwaters. The Bahau, too, is inhabited only at its source, and both rivers pass through wild, picturesque regions. On that portion of the Kayan called Brem-Brem the river presents a formidable array of kihams which defeated the government's attempt to establish communication between Apo Kayan and the debouchure of the river. This was desirable for the sake of provisioning the garrison. An officer of the Dutch army in Borneo told me that from military reports and the testimony of Kenyahs he estimated that the Brem-Brem is a continuous stretch of kihams for thirty kilometres. The Kenyahs had told him that they walked two days and he thought that for four kilometres the river ran underground. These difficult conditions compel the Kenyahs to take another route in their travels to Tandjong Selor, marching over the watershed to the Bahau River, where they make new prahus and then continue the journey. I give a list of subtribes with reserve: Oma-Bakkah, Oma-Lisan, Oma-Kulit, Oma-Lim, Oma-Puah, Oma-Yalan, Oma-Tokkung, Oma-Bakkung, Oma-Bam, Oma-Lung, Oma-Badang, Lepo-Tepó, Lepo-Táo, Lepo-Maot, Lepo-Ké Anda Páh, Lepo-Ké Ang Lung, Lepo-Ké Oma-Lasang. Most of the Lepo are on the Bahau. My informant, who had travelled in the interior, said there was little difference in the languages of these subtribes. The Kenyahs, a few Kayans, and the Katingans mutilate the membrum virile by transpiercing the glans and the urethra, and a piece of brass wire is inserted. A Kenyah tribe (Oma-Badang) in Podjungan, makes two perforations so directed that the wires are crossed.