Each tetrarchy was divided into five provinces, ruled by five chiefs called apo-ulmen; and each province into nine districts, governed by as many ulmen, who were subject to the apo-ulmen, as the latter were to the toquis.
On the east border of the south portion of the basin of the Rio Grande Mindanao is Mt Apo (10,312 ft.), an extinct volcano and the highest elevation in the archipelago.
The Islands Calamignes, manga, Ousl2vda uin/ 'lb ' Vig an ant* .0 S p 14;,f,13‘1 Apo d Pand r,, Tsa.
Rain Hol a,p, /?oa Mill Krc apo P1FaCt¢ rtonvi le; O?Ity a.?'rI a, sto i n p .rian ° earem BrNlmelMihsor5 rys?
The rivers of the narrow mountainous peninsulas form many rapids and cataracts; as the Tondano, draining the lake of the same name to the north-west coast of Minahassa at Menado; the Rano-i-Apo, flowing over the plateau of Mongondo to the Gulf of Amurang; the Poigar, issuing from a little-known lake of that plateau; the Lombagin, traversing narrow canons; and the river of Boni, which has its outfall in the plain of Gorontalo, near the mouth of the Bolango or Tapa, the latter connected by a canal with the Lake of Limbotto.