e most
evil kind of creature conceivable--a man-devil!"

"But what does he want with bats' heads?"

"The Cynonycteris, or pyramid bat, has a leaf-like appendage beside
the nose. A gland in this secretes a rare oil. This oil is one of the
ingredients of the incense which is never named in the magical
writings."

Sime shuddered.

"Here!" said Dr. Cairn, proffering a flask. "This is only the
overture! No nerves."

The other nodded shortly, and poured out a peg of brandy.

"Now," said Dr. Cairn, "shall I go ahead?"

"As you like," replied Sime quietly, and again quite master of
himself. "Look out for snakes. I will carry the light and you can keep
yours handy in case you may need it."

Dr. Cairn drew himself up into the entrance. The passage was less than
four feet high, and generations of sand-storms had polished its
sloping granite floor so as to render it impossible to descend except
by resting one's hands on the roof above and lowering one's self foot
by foot.

A passage of this description, descending at a sharp angle for over
two hundred feet, is not particularly easy to negotiate, and progress
was slow. Dr. Cairn at every five yards or so would stop, and, with
the pocket-lamp which he carried, would examine the sandy floor and
the crevices between the huge blocks composing the passage, in quest
of those faint tracks which warn the traveller that a serpent has
recently passed that way. Then, replacing his lamp, he would proceed.
Sime followed in like manner, employing only one hand to support
himself, and, with the other, constantly directing the ray of his
pocket torch past his companion, and down into the blackness beneath.

Out in the desert the atmosphere had been sufficiently hot, but now
with every step it grew hotter and hotter. That indescribable smell,
as of a decay begun in remote ages, that rises with the impalpable
dust in these mysterious labyrinths of Ancient Egypt which never know
the light of day, rose stiflingly; until, at some forty or fifty feet
below the level of the sand outside, respiration became difficult, and
the two paused, bathed in perspiration and gasping for air.

"Another thirty or forty feet," panted Sime, "and we shall be in the
level passage. There is a sort of low, artificial cavern there, you
may remember, where, although we cannot stand upright, we can sit and
rest for a few moments."

Speech was exhausting, and no further words were exchanged until the
bottom of t