The singing continued, sometimes sinking to a low, droning sound, sometimes rising to a wild wail that sounded weirdly over the marshland.
"Ready," said Frank, and the canoe slipped silently over the dark surface of the water course.
The singing ceased after a time, but they were still guided by the sound of wrangling voices.
"They are quarreling!" exclaimed Frank, softly.
"This is tut-tut-terrible!" stuttered the professor.
Suddenly the sound of a pistol shot came over the rushes, followed by a feminine shriek of pain or terror!
CHAPTER XXX.
FRANK'S SHOT.
Frank and his two companions were profoundly astonished. As soon as he could recover, Frank asked: