Influenced by this fact,and also because they were 483,000,000miles from the sun,instead of 92,000,000as on earth,they had steered for the northern limit of Jupiter's tropics.And,in addition to this,they could easily apply the apergetic power in any degree to themselves when beyond the limits of the Callisto,and so be attracted to any extent,from twice the pull they receive from gravitation on earth to almost nothing.
Bearwarden and Ayrault shouldered their rifles,while Dr.
Cortlandt took a repeating shot-gun with No.4shot,and,having also some hunting-knives and a sextant,all three set out in a northwesterly direction.The ground was rather soft,and a warm vapor seemed to rise from it.To the east the sky was veiled by dense clouds of smoke from the towering volcanoes,while on their left the forest seemed to extend without limit.Clumps of huge ferns were scattered about,and the ground was covered with curious tracks.
"Jupiter is evidently passing through a Carboniferous or Devonian period such as existed on earth,though,if consistent with its size,it should be on a vastly larger scale,"said the doctor.
"I never believed in the theory,"he continued,"that the larger the planet the smaller should be its inhabitants,and always considered it a makeshift,put forward in the absence of definite knowledge,the idea being apparently that the weight of very large creatures would be too great for their strength.Of the fact that mastodons and creatures far larger than any now living on earth existed there,we have absolute proof,though gravitation must have been practically the same then as now."Just here they came upon a number of huge bones,evidently the remains of some saurian,and many times the size of a grown crocodile.On passing a growth of most luxuriant vegetation,they saw a half-dozen sacklike objects,and drawing nearer noticed that the tops began to swell,and at the same time became lighter in colour.Just as the doctor was about to investigate one of them with his duck-shot,the enormously inflated tops of the creatures collapsed with a loud report,and the entire group 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 partially concealed mouth opened,showing the unmistakable tongue and fangs of a serpent.It emitted a hissing sound,and the small eyes gleamed maliciously.
"Do you believe it is a poisonous species?"asked Ayrault.
"I suspect it is,"replied the doctor;"for,though it is doubtless able to leap with great accuracy upon its prey,we saw it took some time to recharge the upper air-chamber,so that,were it not armed with poison glands,it would fall an easy victim to its more powerful and swifter contemporaries,and would soon become extinct.""As it will be unable to spring for some time,"said Bearwarden,"we might as well save it the disappointment of trying,"and,snapping the used shell from his rifle,he fired an explosive ball into the reptile,whereupon about half the body disappeared,while a sickening odour arose.Although the sun was still far above the horizon,the rapidity with which it was descending showed that the short night of less than five hours would soon be upon them;and though short it might be very dark,for they were in the tropics,and the sun,going down perpendicularly,must also pass completely around the globe,instead of,as in northern latitudes on earth in summer,approaching the horizon obliquely,and not going far below it.A slight and diffused sound here seemed to rise from the ground all about them,for which they could not account.Presently it became louder,and as the sun touched the horizon,it poured forth in prolonged strains.The large trumpet-shaped lilies,reeds,and heliotropes seemed fairly to throb as they raised their anthem to the sky and the setting sun,while the air grew dark with clouds of birds that gradually alighted on the ground,until,as the chorus grew fainter and gradually ceased,they flew back to their nests.The three companions had stood astonished while this act was played.The doctor then spoke:
