64 
HAROLD’S DISCUSSIONS. 
numerous species of life. Many of them gradu¬ 
ally developed higher forms, and a new type, the 
vertebrates, is added at the close of the Silurian^ 
when fishes appear. Plants of various species filled 
the sea and covered the low-lying continents. Indeed, 
some of them had reached perfection in the Car¬ 
boniferous age and already began to decline. The 
trilohite and some of his fellow-paddlers passed away 
never again to appear. For a long time it had held 
sway. He was in his glory in the latter part of the 
Silurian age, but after that he slowly waned. The 
changes that time had brought upon him were such 
that his line has been classified into six families. 
This was the era of ancient life known as the 
Paleozoic (paleo, ancient, and zoic, of life), or the era 
of invertebrates, for in the following eras these were 
subordinate to the vertebrates. The changes were so 
great and the life so different from the Paleozoic that 
time since then has been called the neozoic, new life. 
Professor Le Conte sums up the closing Paleozoic 
life thus: “ During the coal age there were extensive 
marshes overgrown with great trees of Sigillaria, 
Lepidodendron, and Calamites, whose dense under¬ 
brush of ferns was inhabited by insects and amphibi¬ 
ans ; no umbrageous trees, no fragrant flowers or lus¬ 
cious fruits, no birds, no mammals. These ‘ dim watery 
woodlands • are fiowerless, fruitless, songless, voice¬ 
less, except the occasional chirp of the grasshopper. 
If the observer were a naturalist he would notice also 
the complete absence of modern types and animals— 
it would be like another world.” 
