His heels mechanically pressed his horse's flanks, and the animal sprang forward.
"Guarda! Mira!" said the voice again in a quicker, lower tone.

But this time it was evidently in the field beside him, and the heads and shoulders of two horsemen emerged at the same moment from the tall ranks of wild oats.

The mystery was solved.

The strangers had been making their way along a lower level of the terraced plain, hidden by the grain, not twenty yards away, and parallel with the road they were now ascending to join.

Their figures were alike formless in long striped serapes, and their features undistinguishable under stiff black sombreros.
"Buenas noches, senor," said the second voice, in formal and cautious deliberation.
A sudden inspiration made Clarence respond in English, as if he had not comprehended the stranger's words, "Eh ?" "Gooda-nighta," repeated the stranger.
"Oh, good-night," returned Clarence.