They now approached a kelp bed, the straight, thin stems of the kelp running far upward to the surface of the water.  Here and there upon the stalks were leaves, but Trot thought the growing kelp looked much like sticks of macaroni, except they were a rich red-brown color.  It was beyond the kelp—­which they had to push aside as they swam through, so thickly did it grow—­that they came to a higher level, a sort of plateau on the ocean’s bottom.  It was covered with scattered rocks of all sizes, which appeared to have broken off from big shelving rocks they observed nearby.  The place they entered seemed like one of the rocky canyons you often see upon the earth.

“Here live the fiddler crabs,” said Merla, “but we must have taken them by surprise, it is so quiet.”

Even as she spoke, there was a stirring and scrambling among the rocks, and soon scores of light-green crabs were gathered before the visitors.  The crabs bore fiddles of all sorts and shapes in their claws, and one big fellow carried a leader’s baton.  The latter crab climbed upon a flat rock and in an excited voice called out, “Ready, now—­ready, good fiddlers.  We’ll play Number 19, Hail to the Mermaids.  Ready!  Take aim!  Fire away!”

At this command every crab began scraping at his fiddle as hard as he could, and the sounds were so shrill and unmusical that Trot wondered when they would begin to play a tune.  But they never did; it was one regular mix-up of sounds from beginning to end.  When the noise finally stopped, the leader turned to his visitors and, waving his baton toward them, asked, “Well, what did you think of that?”

“Not much,” said Trot honestly.  “What’s it all about?”

“I composed it myself!” said the Fiddler Crab.  “But it’s highly classical, I admit.  All really great music is an acquired taste.”

“I don’t like it,” remarked Cap’n Bill.  “It might do all right to stir up a racket New Year’s Eve, but to call that screechin’ music—­”

Just then the crabs started fiddling again, harder than ever, and as it promised to be a long performance, they left the little creatures scraping away at their fiddles as if for dear life and swam along the rocky canyon until, on turning a corner, they came upon a new and different scene.

There were crabs here, too, many of them, and they were performing the queerest antics imaginable.  Some were building themselves into a pyramid, each standing on edge, with the biggest and strongest ones at the bottom.  When the crabs were five or six rows high, they would all tumble over, still clinging to one another and, having reached the ground, they would separate and commence to build the pyramid over again.  Others were chasing one another around in a circle, always moving backward or sidewise, and trying to play “leapfrog” as they went.  Still others were swinging on slight branches of seaweed or turning cartwheels or indulging in similar antics.