which one is correct? 【They were in territory a little west of the prairie's rim where old Slew-foot had fed on fire-plant. Dry weather had sucked up much of the water and the marsh had broad areas that were now firm and dry. The ponds showed plainly. They had withdrawn from the saw-grass and only lily pads troubled the water's surface. A Blue Peter ran across them, bright with yellow legs and painted face. A slight breath of air rippled across the marsh and the water rippled under it. The lily pads tipped, an in-stant, their broad shining leaves to the glint of the sun. "Jest enough of a riffle," Penny said, "and the moon jest right." 】 in the abovecontext, I wonder what does "just enough of a riffle"mean? does Penny is talking about many riffles, or is he satified with one specific riffle..say.. maybe he though that riffle is big enough? Which understanding is correct?