Frank was already strangely interested in the inmates of this little cot, and when Mammy Mop, as the children called her, handed down the great old Bible, and when this brown-faced fisherman read a portion, and afterwards prayed more earnestly and in loftier language than ever the parish minister used, Frank looked at him in reverent wonder not unmixed with awe.
Then they all sat round the fire again.
The wind had now risen and was moaning round the cot, and the rain rattled dismally against it.
Fred shuddered a little as he listened to the wind.
"I'm so glad," he said, "that we went down to-night to our aquarium, to feed the blennies, and a new pet of Toddie's that she called Tom."
"Tom has been naughty," said Toddie, "so Tom has been sent home."
"Yes, that is true," said Fred, "very naughty, and we had gone down to the rocks to put Tom away, else we never should have heard your cry."
The children's aquarium, I may tell you, was a marine one in a cave down by the sea. The cave was a shallow one in the south side of the ridge of high cliffs that ran out to sea, but far removed beyond the avaricious clutch of a rising tide unless something out of the common should occur. Bodily the sea had never risen so high as Fred's cave in his time, although in days of storm and tempest, when great green waves broke and thundered on the beach, the spray was often carried far along the face of the cliffs with force enough to drench anyone to the skin who ventured as far as the cave; once inside, however, one was safe enough. Not more than ten feet in depth or width was the cave, though more than nearly twenty feet high, and a very pleasant place to spend an hour or two in by day during the summer months. At noon the sun shone right into it, and penetrated the water of Fred's aquarium at the end. This latter was a natural basin in the rock, a kind of hollow shelf about three feet above the floor, which these children kept filled with water, and stocked with many curious creatures, that they found upon the beach, such as shell fish, tiny medusæ, sea anemones, and little fishes of many kinds. Toddie delighted in droll, weird-looking water things, and used to shout aloud for joy when she found any new form of youthful marine monster left in a pool of the rocks when the tide went back. She never went seawards without Fred, and he carried a little hand landing-net, and whenever a fresh specimen was discovered ugly enough to commend itself to Toddie, she peremptorily ordered her chaperon to fish it out and convey it to the cave aquarium.
Things throve here very well indeed, owing perhapa to the fact that they kept the water constantly changed and carefully removed any wee creature that died. Singularly enough, however, soon after the arrival of Tom, specimens began to disappear in the most mysterious manner.
But it is time to explain who Tom was. Watching the fishermen drawing in their nets one day, in which was a goodly quantity of bonnie silver herrings, Toddie noticed one of the men pull a strange-looking fish out of the net and throw it inland to die. Toddie went straight away after it. The creature had fallen among a lot of dry seaweed, so it was none the worse, though it wriggled alarmingly when the girl lifted it up and put it in her apron. In ten minutes' time she had placed it in Fred's cave aquarium, where it rested on its side a short time, then began a tour of inspection much to Toddie's delight. A long stone-grey, light-spotted thing, with a semicircular mouth away under its chin, and a tail with one half of it much longer than the other. In fact it was that species of small shark that abounds round British coasts, called the dog-fish.