It had two tails, scaly and powerful-looking, and a barrel-shaped body rippling with muscle.

It was unlike anything I could describe. It could not exist—but it did!

The heela stopped a few yards away and its twin tails lashed as it regarded us with its two pairs of eyes.

The only thing to its advantage, as far as I could see, was that it measured only about half the size of an ordinary dahara.

Yet it still looked dangerous and could easily dispose of me, I knew.

Then it sprang. Not at me and not at Darnad— but at the head of Darnad's dahara.

The poor animal shrieked in pain and fear as the heela sank its eight sets of talons into its great flat head and simply clung there, biting with its two sets of teeth at the dahara's spinal cord.

Darnad began to hack at the heela with his sword. I tried to move in to help him but my animal refused to budge.

I dismounted—it was the only thing I could do— and paused behind the clinging heela's back. I did not know much about Martian biology, but I selected a spot on the heela's neck corresponding to the place where he was biting the dahara. I knew that many animals will go for a spot on other species which corresponds with their own vital spots.

I plunged my sword in.

For a few moments the heela still clung to the dahara's head; then it released its grip and with a blood-curdling scream of anguish and fury fell to the mossy ground. I stood back, ready to meet any attack it might make. But it got up, stood shakily on its legs, took a couple of paces away from me— and then fell dead.

Meanwhile, Darnad had dismounted from the dahara, now moaning in pain and stamping on the moss.

The poor beast's flesh had been ripped away from a considerable area of its head and neck. It was beyond any help we could give it—save to put it out of its pain.

Regretfully, I saw Darnad place his sword against the creature's head and drive it home, wincing as he did so.

Soon dahara and heela lay side by side. A useless waste of life, I reflected.

What was more, we should now have to ride double and though my dahara was strong enough to carry both of us, we should have to travel at about half our previous speed.

Bad luck was dogging us, it seemed.