“I need not say,” said our leader, “that on the occasion of my last visit I exhausted every means of climbing the cliff, and where I failed I do not think that anyone else is likely to succeed, for I am something of a mountaineer.  I had none of the appliances of a rock-climber with me, but I have taken the precaution to bring them now.  With their aid I am positive I could climb that detached pinnacle to the summit; but so long as the main cliff overhangs, it is vain to attempt ascending that.  I was hurried upon my last visit by the approach of the rainy season and by the exhaustion of my supplies.  These considerations limited my time, and I can only claim that I have surveyed about six miles of the cliff to the east of us, finding no possible way up.  What, then, shall we now do?”

“There seems to be only one reasonable course,” said Professor Summerlee.  “If you have explored the east, we should travel along the base of the cliff to the west, and seek for a practicable point for our ascent.”

“That’s it,” said Lord John.  “The odds are that this plateau is of no great size, and we shall travel round it until we either find an easy way up it, or come back to the point from which we started.”

“I have already explained to our young friend here,” said Challenger (he has a way of alluding to me as if I were a school child ten years old), “that it is quite impossible that there should be an easy way up anywhere, for the simple reason that if there were the summit would not be isolated, and those conditions would not obtain which have effected so singular an interference with the general laws of survival.  Yet I admit that there may very well be places where an expert human climber may reach the summit, and yet a cumbrous and heavy animal be unable to descend.  It is certain that there is a point where an ascent is possible.”

“How do you know that, sir?” asked Summerlee, sharply.

“Because my predecessor, the American Maple White, actually made such an ascent.  How otherwise could he have seen the monster which he sketched in his notebook?”

“There you reason somewhat ahead of the proved facts,” said the stubborn Summerlee.  “I admit your plateau, because I have seen it; but I have not as yet satisfied myself that it contains any form of life whatever.”

“What you admit, sir, or what you do not admit, is really of inconceivably small importance.  I am glad to perceive that the plateau itself has actually obtruded itself upon your intelligence.”  He glanced up at it, and then, to our amazement, he sprang from his rock, and, seizing Summerlee by the neck, he tilted his face into the air.  “Now sir!” he shouted, hoarse with excitement.  “Do I help you to realize that the plateau contains some animal life?”

I have said that a thick fringe of green overhung the edge of the cliff.  Out of this there had emerged a black, glistening object.  As it came slowly forth and overhung the chasm, we saw that it was a very large snake with a peculiar flat, spade-like head.  It wavered and quivered above us for a minute, the morning sun gleaming upon its sleek, sinuous coils.  Then it slowly drew inwards and disappeared.