soared away. When about to alight, forty yards off, they
distended membranous folds in the manner of wings, which checked
their descent, and on touching the ground remained where they
were without rebound.

"We expected to find all kinds of reptiles and birds," exclaimed
the doctor. "But I do not know how we should class those
creatures. They seem to have pneumatic feet and legs, for their
motion was certainly not produced like that of frogs."

When the party came up with them the heads again began to swell.

"I will perforate the air-chamber of one," said Col. Bearwarden,
withdrawing the explosive cartridge from the barrel of his rifle
and substituting one with a solid ball. "This will doubtless
disable one so that we can examine it."

Just as they were about to rise, he shot the largest through the
neck. All but the wounded one, soared off, while Bearwarden,
Ayrault, and Cortlandt approached to examine it more closely.

"You see," said Cortlandt, "this vertebrate--for that is as
definitely as we can yet describe it--forces a great pressure of
air into its head and neck, which, by the action of valves, it
must allow to rush into its very rudimentary lower extremities,
distending them with such violence that the body is shot upward
and forward. You may have noticed the tightly inflated portion
underneath as they left the ground."

While speaking he had moved rather near, when suddenly a