"Oh, come," laughed Billy, "I've heard of tailed men and white
Africans with red top-knots like Lathrop, but a race of winged men
is coming it too strong."

"Laugh if you like," declared Professor Wiseman who had brought up
the subject, "but some time ago I articulated a skeleton brought me
by an Arab slave trader and found extending from the shoulder blade
two distinct bony frames which had in life apparently been covered
with a thin fleshy substance of leathery like tenacity stretching
thence to the wrists. I asked the slave trader where he had found
the skeleton," went on the savant, "and he told me he had come
across it at the foot of a giant silk cotton tree in the Bambara
country."

The boys exchanged glances. It was to the Bambara country--the
country of the legendary Flying Men--that they were bound.

"Is any more known of this tribe?" inquired Frank.

"Very little except what you can pick up from the natives, which is
little enough," replied Professor Wiseman, "they seem to have a
dislike to speaking of the Flying Men--to whites at any rate. I
think, too, they fear them. Report has it that they live in
cave-like holes in the side of a giant, black basalt cliff reached
by a subterranean river. They reach the ground by taking short
flights from the holes they live in and regain the cliff dwellings
by means of rope ladders formed of twisted creepers."

"Then they cannot fly upward?" asked Frank.