I started to haul in the deep-level net. It came up. Something kicked feebly. It must have been a fish, because it came out of the sea. It had a peculiar flat head and a protruding beak. The etiolated tail looked as if it had been put through a mangle. The underlying colour was lead, but near the surface the skin was a phosphorescent shocking pink. The eyes. !

My exclamation brought Sailhardy over. The fish's eyes pointed in one direction only-upwards. It was horrible. It gazed as if in supplication. It was about eighteen inches long. I held it at arm's length and I saw that the eyes were fixed to look permanently upwards.

Sailhardy stopped me from throwing it overboard. He took it and held it affectionately. The upturned, dying eyes winced in the sun.

" This is it, Bruce," he said quietly.

The thing writhed in his grip.

" This is an abyssal fish," he went on. " It comes from the deeps. He looks up-to see his food above him. He lives only on plankton."

" Plankton!" I exclaimed. " There wasn't a sign of plankton!" He went as taut as a jib sheet in a blow. His eyes were on something near the kelp barrier of Tristan.

" Longfin!" he said with satisfaction. " Longfin! And bluefin!"

There was nothing in sight except Tristan, which seemed hazier. Clouds were starting to lock round the old volcano. " What is it, man?" I exclaimed.

" Tunny," he replied. " Tunny."

There was a momentary flash from the surface of the sea near the kelp barrier.

" That was the forward fin of a tunny," he said crisply. " His aft dorsal fin stays erect, but the forward one he can fold and unfold at will. He does so when he wants to make a quick turn. He shoots it upright for a moment and swings round hard on it. The tunny wouldn't be doing it unless they were feeding-and feeding hard. That means. .."