At the end of the boys’ story, Brenda asked:  “The thieves were a Mexican and an American?”

“Yes.”

“The American had a scar on the bridge of his nose, and the Mexican had lost his front teeth?”

“Exactly.  What do you know about them, Brenda?”

“They were here, but I did not see their ponies nearer than the stable; they were black and cream color.  The Mexican traded saddles with uncle.  You’ll find the one he left in the lean-to, on a peg beside the door.”

Both boys leaped to the ground and ran round the house to the lean-to, and presently returned with Henry’s neat McClellan saddle.  It had been stripped of its pouches and small straps, but was otherwise unharmed.

“Well, when I come back with Chiquita, Mr. Arnold, I’d like to trade saddles.”

“All right, youngkett, I’ll trade, or you can take it now, and welcome,” replied the ranchman.

“No; I’ll leave it until I return.”

The saddle was taken back to the lean-to, and after a few more words of leave-taking we started up the valley.  A few miles of rapid travelling brought us to a steep ascent into a mountainous range to the right.  We had proceeded but a short distance through a narrow and rugged roadway when we were overtaken by the military expressman whom we had left at Fort Whipple.  He had come from Prescott to Skull Valley by a short cut.

“I have a letter for you, lieutenant,” said he, approaching the ambulance.

Unfastening the mail-pouch, he turned its contents upon the back seat.  A heap of loose letters and three well-worn books strewed themselves over the cushion.  Frank picked up the books and examined their titles.

“Xenophon’s Memorabilia, Euripides’ Alcestis and Medea, and a Greek grammar!” exclaimed the astonished youngster.  “What are you doing with these college text-books on the La Paz trail?”

“Making up conditions,” replied the courier, a blush deepening the brown of his face.

“What are conditions?” asked Henry.

“Oh, blissful ignorance!  Why was I not spared the task of enlightening it?” answered the courier.  “Conditions are stumbling-blocks placed in the way of successful trackmen, football players, and rowing men by non-appreciative and envious professors.”

“‘Joseph Gould Hudson, University of Yalvard,’” read Frank from the fly-leaf of the Memorabilia.  “Is that your name, Mr. Hudson?”

“I’m so borne on the Yalvard catalogue.”

“Please explain, Mr. Hudson,” I said, “how a college boy happens to be in Arizona running the gantlet of this mail-route and making up conditions in Greek?”

“I was stroke in the crew that won the championship for Yalvard at New London one year ago, and got behind in these.  I was conditioned, and being ashamed to face an angry father, struck out for myself on the Pacific coast.  I drifted about from mining-camp to cattle-range until I was dead broke; this place offered, and I took it because I could find nothing else.  I’ve had lots of opportunities for reflection on the Xuacaxella.  I’m the repentant prodigal going home to his father.”