It took us three hours of whacking and slashing and tearing to pull the fish to pieces, but we worked with a purpose and a will.  When we had finished, this is what we had to show:  A long strip of bone, four inches thick and twelve feet long, and tough as hickory, from either side of which the smaller bones projected at right angles.  They were about an inch in thickness and two inches apart.  The lower end of the backbone, near the tail, we had broken off.

We examined it and lifted it and bent it half double.

“Absolutely perfect!” Harry cried in jubilation.  “Three more like this and we’ll sail down the coast to Callao.”

“If we can get ’em,” I observed.  “But two would do.  We could make it a triangle.”

Harry looked at me.

“Paul, you’re an absolute genius.  But would it be big enough to hold us?”

We discussed that question on our way back to camp, whither we carried the backbone of our fish, together with some of the meat.  Then, after a hearty meal, we slept.  After seven hours of the hardest kind of work we were ready for it.

That was our program for the time that followed—­time that stretched into many weary hours, for, once started, we worked feverishly, so impatient had we become by dint of that faint glimmer of hope.  We were going to try to build a raft, on which we were going to try to embark on the stream, by which we were going to try to find our way out of the mountain.  The prospect made us positively hilarious, so slender is the thread by which hope jerks us about.

The first part of our task was the most strenuous.  We waited and waded round many hours before another fish appeared, and then he got away from us.  Another attempt was crowned with success after a hard fight.  The second one was even larger than the first.

The next two were too small to be of use in the raft, but we saved them for another purpose.  Then, after another long search, lasting many hours, we ran into half a dozen of them at once.

By that time we were fairly expert with our spears, besides having discovered their vulnerable spot—­the throat, just forward from the gills.  To this day I don’t know whether or not they were man-eaters.  Their jaws were roomy and strong as those of any shark; but they never closed on us.

Thus we had four of the large backbones and two smaller ones.  Next we wanted a covering, and for that purpose we visited the remains of the reptile which had first led us into the cavern.

Its hide was half an inch thick and tough as the toughest leather.  There was no difficulty in loosening it, for by that time the flesh was so decayed and sunken that it literally fell off.  That job was the worst of all.

Time and again, after cutting away with the points of our spears—­our only tools—­until we could stand it no longer, we staggered off to the stream like drunken men, sick and faint with the sight and smell of the mess.