"I've got it," he exclaimed, "and I'm a plum-busted idjut not to have thought uv it afore; I've hearn about 'em often enough. This here backterian camel must be one of that bunch of Circus Jesse's." "Circus Jesse! Who was he, or she?" asked Jack. "Why, he was a feller what owned a big eastern circus, but owned a ranch out here as well. It struck him one time that if camels was good for transportation purposes over the Sahara desert they ought ter be just as good here. So, what does he do but start a camel express from Maguez ter Amadillo over the border, with some of the backterians frum his circus." "And didn't it work?" asked Ralph. "No. That is, it did fer a while, till ther novelty wore off, and then folks went back ter ther old reliable mule or burro. Circus Jesse, he got so blamed sore, that one fine day he turned the whole shootin' match of his backterians loose, and packin' his trunk, let the country, and resolved in futur' ter stick ter his circus." "Was that long ago?" asked Jack. "I shouldn't have thought the creatures would have lived long without being recaptured." "It's about five years since Jesse got out, I reckon," rejoined Pete, "an' fer a while camel-hunting was a popular sport. By an' by, however, they got so wary no one could get near 'em, and, except fer a scare they'd throw inter a prospector now and ag'in, we never heard no more of 'em. I'd clean fergotten all about 'em, till I made this one inter cold backterian meat." "I suppose they found food and water here and regarded the Mesa as their own property," declared Jack. "That's about it. This is a place that's seldom visited, and I guess they just figgered out that they'd found a happy home." "But what became of the rest of them?" asked Ralph, who had been apprised by Jack of the strange vanishment of the dead creature's mates. "Must uv gone down that draw I noticed frum ther top uv ther mesa to-day," explained Pete. "Yer see, frum here, it would look as if they vanished inter the solid earth when they entered it, bein' as how you can't see there's any kind of a gully there till you get up high." The next morning this was found to be the true explanation. Tracks on the bottom of the gully showed plainly how the strange desert wanderers had effected their disappearance in such a startling manner. But it was some time before Pete could sit down to a meal without being reminded of his "fire-spouting spook," which had cast such alarm into the camp the first night. The boys spent a week more at the mesa, during which time Professor Wintergreen obtained voluminous notes on one of the most interesting specimens of its kind in the south-west. The days passed tranquilly, and, with the exception of the duty of removing the carcass of the dead camel, nothing to interrupt the routine of survey work occurred. The mates of the dead beast had evidently decided not to revisit their pasture grounds, for they did not put in a reappearance.