Europe as a continent did not exist. A few islands showed their heads above the waves where Germany and Switzerland, Eastern France and Spain now stand. Scotland's rocky islets were probably visible, on the extreme west, though these islands were destined to sink again below the waves. Thence the ocean stretched without a break, as at present, to Canada. A great part of Canada's bleak lands was above the waters; but the United States, except for a few great islands, were submerged. In the southern hemisphere South America, split into numerous long reefs and islands, gave promise of the continent to be; and there were great stretches of land over Brazil, extending to the west where the great chains of mountains now rise. Asia was largely covered with shallow waters, and the whole extent of the northern plains of Africa was sea. So far as we are able to judge the distinctions of climates were less marked then than now, and the conditions seem to have been much more uniform over all the northern hemisphere. This equality of climate lasted into the next or Ordovician period. The Ordovician period glides insensibly into the Cambrian. There was no distinct break in the succession of life. The species seem to have slowly extended and developed from one of these great periods into another. But the life of the Ordovician era, which has been preserved for us, is much more abundant. Land was beginning to emerge from the sea in greater bulk; life was springing up on the land and was emerging from the sea, perhaps to take up its habitation there. The first insect life appears in the Ordovician. It is not an imposing relic except when seen through the eye of imagination. It is just an obscure wing of an insect which was found impressed on some shales found in the upper Ordovician rocks of Sweden, and all we can say of it is that it belonged to the same class of insects as lady-birds. The existence of this insect shows that there must have been land vegetation and an atmosphere which was suited to active air-breathing things. The other appearance of great interest in the Ordovician rocks is that of the first fish. They were found in Colorado, but they are very much shattered and tell us very little about the animals they represent. These fish were covered with plates, and were evidently thus defended against attack, so that we may surmise the existence of some other animal that preyed on fishes. Whether these fishes were themselves ferocious we cannot, however, say. But that which was the chief characteristic of the Ordovician era was the climax of the trilobite. More than half of all the known trilobites were present in Ordovician times. Only a few of these came over from the Cambrian, while the others make their first appearance in this period. In the next period (Silurian) their numbers fell to one half, and in later periods declined still further, till they disappeared altogether at the close of the Palæozoic era. Some of these curious