A distant ululation of howling monkeys filled the sultry night with foreboding sounds, and as the gunboat drew near the black mysterious banks this was reinforced by a depressing clamour of frogs.

It shook again through the heavy, oppressive night, merely accentuated by the candlea faint ululation barely detaching itself from silence, straying after a time into the silence again.

His ears, strained to the alert, caught it above the drums and voicesa thin, high ululation.