While washing their knives in the stream preparatory to leaving it--for they wished to return to the Callisto by completing the circle they had begun--they noticed a huge flat jelly-fish in shallow water. It was so transparent that they could see the sandy bottom through it. As it seemed to be asleep, Bearwarden stirred up the water around it and poked it with a stick. The jelly-fish first drew itself together till it touched the surface of the water, being nearly round, then it slowly left the stream and rose till it was wholly in the air, and, notwithstanding the sunlight, it emitted a faint glow.
"Ah!" exclaimed Bearwarden, "here we have one of our Jack-o'-lanterns. Let us see what it is going to do."
"It is incomprehensible to me," said Cortlandt, "how it maintains itself; for it has neither wings nor visible means of support, yet, as it was able to immerse itself in the stream, thereby displacing a volume of liquid equivalent to its bulk, it must be at least as heavy as water."
The jelly-fish remained poised in the air until directly above them, when it began to descend.
"Stand from under!" cried Bearwarden, stepping back. "I, for one, should not care to be touched."
The great soft mass came directly over the spot on which they had been standing, and stopped its descent about three feet from the ground, parallel to which it was slowly carried by the wind. A few yards off, in the direction in which it was moving, lay a long black snake asleep on the sand. When directly over its victim the jelly globule again sank till it touched the middle of the reptile's back. The serpent immediately coiled itself in a knot, but was already dead. The jellyfish did not swallow, but completely surrounded its prey, and again rose in the air, with the snake's black body clearly visible within it.
"Our Will-o'-the-wisp is prettier by night than by day," said Bearwarden. "I suggest that we investigate this further."
"How?" asked Cortlandt.
"By destroying its life," replied Bearwarden. "Give it one barrel from your gun, doctor, and see if it can then defy gravitation."
Accordingly Cortlandt took careful aim at the object, about twenty-yards away, and fired. The main portion of the jellyfish, with the snake still in its embrace, sailed away, but many pounds of jelly fell to the ground. Most of this remained where it had fallen, but a few of the larger pieces showed a faint luminosity and rose again.