deny that it has its holy aspects."

"Get your hand away, will you, Peters?" asked Janus.

I did. When Janus's camera had clicked, I bent again and peered through the hole. "It sights on that low ridge over there," I said. "Maybe it's some kind of surveying setup. I'm going to take a look."

"Careful," warned Janus. "Remember, it may be sacred."

As I walked away, I heard Allenby say, "Take some scrapings from the inside of the hole, Gonzales. We might be able to determine if anything is kept in it...."

One of the stumpy, purplish, barrel-type cacti on the ridge had a long vertical bite out of it ... as if someone had carefully carved out a narrow U-shaped section from the top down, finishing the bottom of the U in a neat semicircle. It was as flat and cleancut as the inside surface of a horseshoe magnet.

I hollered. The others came running. I pointed.

"Oh, my God!" said Allenby. "Another one."

The pulp of the cactus in and around the U-hole was dried and dead-looking.

Silently Burton used his tape-measure. The hole measured four and three-eighths inches across. It was eleven inches deep. The semicircular bottom was about a foot above the ground.

"This ridge," I said, "is about three feet higher than where we landed the ship. I bet the hole in the rock and the hole in this cactus are on the same level."

Gonzales said slowly, "This was not done all at once. It is a result of periodic attacks. Look here and here. These overlapping depressions along the outer edges of the hole—" he pointed—"on this side of the cactus. They are the signs of repeated impact. And the scallop effect on this side, where whatever made the hole emerged. There are juices still oozing—not at the point of impact, where the plant is desiccated, but below, where the shock was transmitted—"

A distant shout turned us around. Burton was at the rock, beside the ship. He was bending down, his eye to the far side of the mysterious hole.

He looked for another second, then straightened and came toward us at a lope.

"They line up," he said when he reached us. "The bottom of the hole in the cactus is right in the middle when you sight through the hole in the rock."

"As if somebody came around and whacked the cactus regularly," Janus said, looking around warily.

"To keep the line of sight through the holes clear?" I wondered. "Why not just remove the cactus?"

"Religious," Janus explained.

The gauntlet he had discarded lay ignored on the ground, in the shadow of the cactus. We went on past the ridge toward an outcropping of rock about a hundred yards farther on. We walked silently, each of us wondering if what we half-expected would really be there.

It was. In one of the tall, weathered spires in the outcropping, some ten feet below its peak and four feet above the ground, was a round four-inch hole.

Allenby sat down on a rock, nursing his ankle, and remarked that anybody who believed this crazy business was really happening must have holes in the rocks in his head.

Burton put his eye to the hole and whistled. "Sixty feet long if it's an inch," he said. "The other end's just a pinpoint. But you can see it. The damn thing's perfectly straight."

I looked back the way we had come. The cactus stood on the ridge, with its U-shaped bite, and beyond was the ship, and beside it the perforated rock.

"If we surveyed," I said, "I bet