We now enter upon the ancient life, or Palæozoic period of the earth’s history, and proceed to examine the oldest forms of life, or the most ancient organic remains found in the crust of the earth. As we do not aim to _teach_ geology in this small work, but simply to place the chief geological facts in such a light as to impart a _taste_ for the science, the reader will not expect any minute details, which are more likely to perplex than to assist the beginner. Let the reader dismiss from his mind all that he has tried to remember about Upper and Lower Silurian rocks, and the Upper and Lower Ludlow rocks, the Caradoc sandstone and the Llandilo flags, and so on; let us simply say that one part of the crust of the earth, supposed to be between 50,000 and 60,000 feet in thickness,[28] is called the Silurian system, and constitutes a large and interesting part of the Palæozoic period. The term Silurian was given to this part of the earth’s crust in consequence of these rocks being found chiefly in Wales, Devon, and Cornwall—parts of England once inhabited by the Silures, who under Caractacus made so noble a stand against the Romans. In coming for the first time into contact with the organic remains of pre-Adamite creations, it may be well to entreat the student to mark, as he goes on, the very different and characteristic fossils of the several formations through which we propose to travel. There will be little or no difficulty in doing this, and its mastery will be of invaluable service in our after researches. There is and there can be no royal road to any kind of learning; all, therefore, that we propose to do is to take a few of the big stones, boulders, &c., that have needlessly been allowed to make the road rougher than necessary, out of the way, that thus our companion traveller on this geologic route may feel that every step of ground walked over is a real and solid acquisition. In marking the characteristic fossils of each formation, let us suggest, in passing, the vast amount of pleasure there is in going to a friend’s house, and looking at the minerals or organic remains that may be in the cabinet or on the mantel-shelf, and being able to take them up one by one, and to say this is from the Silurian; that is from the Carboniferous; this is from the Cretaceous, and that from the Wealden formations, and so on. Why, it gives a magical feeling of delightful interest to every object we see, and will always make a person a welcome visitor with friends with whom, instead of talking scandal, he can talk geology. Not long since the writer had a very pleasing illustration of this. He had been lecturing on geology in a small agricultural village; there was a good sprinkling of smock-frocks among the hearers, and he said at the close of one of the lectures, “Now, very likely most of you have got some stones, as you call them, at home on the chimneypiece; perhaps you don’t know their names, or what they were before they became