May 13th. We left Mandavaca at half past two in the morning. After six hours of travelling we passed the mouth of the Idapa or Siapa on the east. It rises on the Uturan mountain. It has white waters. Its upper course has been strangely misrepresented on La Cruz's and Surville's maps, which all later maps have imitated. We stopped near the Cunuri raudal. The noise of the little cataract got much louder during the night. Our Indians said that meant certain rain. It fell before sunrise. However, the araguato monkeys' continuous wails had warned us that rain was approaching.