The night darkens down, becoming so obscure that each horseman can barely distinguish the form of him riding ahead.

Some regret this, thinking they may get strayed.

Not so Cully.
On the contrary, the guide is glad, for he feels confident in his conjecture that the pursued will be found in Pecan Creek, and a dark night will favour the scheme of attack he has conceived and spoken of.
Counselled by him, the Ranger captain shares his confidence, and they proceed direct towards the point where the tributary stream unites with the main river--the little Witchita, along whose banks they have been all that day tracking.

Not but that Cully could take up the Indian trail.

Despite the obscurity he could do that, though not, as he jestingly declared, by the smell.