of these first swamp forests constitute the main coal-measures of the world to-day.
Amidst this luxuriant primitive vegetation crawled and glided and flew the first insects. They were rigid-winged, four-winged creatures, often very big, some of them having wings measuring a foot in length. There were numerous dragon flies—one found in the Belgian coal-measures had a wing span of twenty-nine inches! There were also a great variety of flying cockroaches. Scorpions abounded, and a number of early spiders, which, however, had no spinnerets for web making. Land snails appeared. So too did the first-known step of our own ancestry upon land, the amphibia. As we ascend the higher levels of the Later Palæozoic record, we find the process of air adaptation has gone as far as the appearance of true reptiles amidst the abundant and various amphibia.
The land life of the Upper Palæozoic Age was the life of a green swamp forest without flowers or birds or the noises of modern insects. There were no big land beasts at all; wallowing amphibia and primitive reptiles were the very highest creatures that life had so far produced. Whatever land lay away from the water or high above the water was still altogether barren and lifeless. But steadfastly, generation by generation, life was creeping away from the shallow sea-water of its beginning.
- This, says Mr. R. I. Pocock, has to be qualified. There were Carboniferous spiders with spinnerets, though they may have used the silk only for egg cases. And he thinks that the Carboniferous myriapods point to ground beneath the trees.