At last Daisy got him upon the subject of trilobites. It was not difficult. Dr. Sandford was far more easy to move than Preston--in this matter at least. He only smiled, and slid into the story very simply; the story that Daisy was so eager to hear. And it did not seem less worth hearing than she had expected, nor less wonderful, nor less interesting. Daisy thought about it a great deal, while Juanita listened and doubted; but Daisy did not doubt. She believed the doctor told her true. That the family to which her little fossil trilobite belonged--the particular family--for they were generally related, he said to the lobster and crab, were found in the very oldest and deepest down rocks in which any sort of remains of living things have been found; therefore it is likely they were among the earliest of earth's inhabitants. There were a great many of them, the doctor said, and many different species; for great numbers of them are found to this day in those-particular rocks. The rocks must have been made at the time when the trilobites lived, and have somehow shut them in. And the doctor thought it likely that at the time when they lived, there was no dry land in existence, but all covered by the sea. He would not take it upon him to be positive; but this he could tell Daisy; there was never a stick or a leaf to be found in those old rocks that ever lived and grew on dry ground, though there were plenty that grew in the sea, until in the very topmost or latest of those rocks some few bits of fern growth began to appear. "But what plants live under water?" said Daisy. "Sea weeds." "Oh! So many of them?" "So many, that the rocks are sometimes darkened by their fossil remains, and in some places those remains form beds of coal several feet thick." "And are there a great many remains of the trilobites?" "There are whole rocks, Daisy, that are formed almost entirely of trilobites." "Sea weeds and trilobites--what a strange time!" said Daisy. "Was that all that was living?" "No; there were other sea creatures of the lower kind, and at last fishes. But when the fishes became very numerous, the trilobites died out and passed away." That old time had a wonderful charm for Daisy; it was, as she thought, better than a fairy tale. The doctor at last let her into the secret that _he_ had a trilobite too; and the next time he came he brought it with him. He was good enough to leave it with Daisy a whole day; and Daisy's meditations over it and her own together were numberless and profound.