We will suppose, then, that the visitor has gratified his sense of wonder in gazing at the larger and more striking forms, few in number, that rise up prominently before him, and seem to stare at him in return from their hollow sockets: he must next turn his attention to the cases that stand against the walls, and to the cabinets that stretch along the galleries in distant perspective. Let him survey that multitude of bones of every shape and size, and those countless legions of shells, and then try to realize to his mind what a profusion and variety of animal life are here represented. And yet he must remember that this is but a single collection. There are thousands of others, public and private, scattered over England, France, Germany, Italy, and beyond the Atlantic, on the continent of America, and even in Australia; all of which have been furnished from a few isolated spots,--scarcely more than specks on the surface of the Globe,--where the interior of the Earth’s Crust has chanced to be laid open to the explorations of the Geologist. Lastly, before he leaves this splendid gallery, let him take a passing glance at the Organic Remains of the vegetable world. There is no mistaking the forms here presented to his view. He will recognize at once the massive and lofty trunks of forest trees with their spreading branches; the tender foliage of the lesser plants; and, in particular, the graceful fern, which cannot fail to attract his eye by its unrivalled luxuriance. But if the forms are familiar, how strange is the substance, of this ancient vegetation! The forest tree has been turned into sandstone; many of the plants are of the hardest flint; and the rich green of the fern has given place to the jet black color of coal. Let him take a magnifying glass and scrutinize the internal structure of these mineralized remains; for the more closely they are examined the more wonderful do they appear. He can observe without difficulty their minute cells and fibres, the exact counterpart of those which may be seen in the plants that are now growing upon the earth; he may detect the little seed-vessels on the under surface of the coaly fern; nay, if he gets a polished transverse section of the sandstone tree, he may count the rings that mark its annual growth, and tell the age it attained in its primeval forest. [Illustration: Fig. 13.--Fossil Wood, from the Carboniferous Limestone of Mayo, showing the rings of Annual Growth.] [Illustration] [Illustration] _CHAPTER XI._ FOSSIL REMAINS--THE EXPLORATION.