On these rocks, in the midst of slippery wrack, abounded bivalve shell-fish, not to be despised by starving people. Herbert called Pencroft, who ran up hastily.

"Here are mussels!" cried the sailor; "these will do instead of eggs!"

"They are not mussels," replied Herbert, who was attentively examining the molluscs attached to the rocks; "they are lithodomes."

"Are they good to eat?" asked Pencroft.

"Perfectly so."

"Then let us eat some lithodomes."

The sailor could rely upon Herbert; the young boy was well up in natural history, and always had had quite a passion for the science. His father had encouraged him in it, by letting him attend the lectures of the best professors in Boston, who were very fond of the intelligent, industrious lad. And his turn for natural history was, more than once in the course of time, of great use, and he was not mistaken in this instance. These lithodomes were oblong shells, suspended in clusters and adhering very tightly to the rocks. They belong to that species of molluscous perforators which excavate holes in the hardest stone; their shell is rounded at both ends, a feature which is not remarked in the common mussel.

Pencroft and Herbert made a good meal of the lithodomes, which were then half opened to the sun. They ate them as oysters, and as they had a strong peppery taste, they were palatable without condiments of any sort.

Their hunger was thus appeased for the time, but not their thirst, which increased after eating these naturally-spiced molluscs. They had then to find fresh water, and it was not likely that it would be wanting in such a capriciously uneven region. Pencroft and Herbert, after having taken the precaution of collecting an ample supply of lithodomes, with which they filled their pockets and handkerchiefs, regained the foot of the cliff.

Two hundred paces farther they arrived at the cutting, through which, as Pencroft had guessed, ran a stream of water, whether fresh or not was to be ascertained. At this place the wall appeared to have been separated by some violent subterranean force. At its base was hollowed out a little creek, the farthest part of which formed a tolerably sharp angle. The watercourse at that part measured one hundred feet in breadth, and its two banks on each side were scarcely twenty feet high. The river became strong almost directly between the two walls of granite, which began to sink above the mouth; it then suddenly turned and disappeared beneath a wood of stunted trees half a mile off.

"Here is the water, and yonder is the wood we require!" said Pencroft. "Well, Herbert, now we only want the house."

The water of the river was limpid. The sailor ascertained that at this time--that is to say, at low tide, when the rising floods did not reach it --it was sweet. This important point established, Herbert looked for some cavity which would serve them as a retreat, but in vain; everywhere the wall appeared smooth, plain, and perpendicular.

However, at the mouth of the watercourse and above the reach of the high tide, the convulsions of nature had formed, not a grotto, but a pile of enormous rocks, such as are often met with in granite countries and which bear the name of "Chimneys."

Pencroft and Herbert penetrated quite far in among the rocks, by sandy passages in which light was not wanting, for it entered through the openings which were left between the blocks, of which some were only sustained by a miracle of equilibrium; but with the light came also air--a regular corridor-gale--and with the wind the sharp cold from the exterior. However, the sailor thought that by stopping-up some of the openings with a mixture of stones and sand, the Chimneys could be rendered habitable. Their geometrical plan represented the typographical sign "&," which signifies "et cetera" abridged, but by isolating the upper mouth of the sign, through which the south and west winds blew so strongly, they could succeed in making the lower part of use.

"Here's our work," said Pencroft, "and if we ever see Captain Harding again, he will know how to make something of this labyrinth."

"We shall see him again, Pencroft," cried Herbert, "and when be returns he must find a tolerable dwelling here.