482 KANSAS CITY REVIEW OF SCIENCE. 



we can but acknowledge that they represent the life of the period, when as soft 

 mud, this limestone was lying in the bottom of the ocean. And so by natural 

 causes have all the geological records been kept. Many people suppose that the 

 study of geology is dry and stupid, of old bones and rocks. But there is no 

 wider field for the imagination than to people the old seas and lands with animals 

 restored from their buried relics, to clothe the ancient lands with verdure, and 

 map out the continents, study their physical geography, the depth of the sea, 

 climate, and above all to study the introduction and succession of life on the 

 globe and other manifold changes brought about in the animal creation, their de- 

 velopment from lowly forms, and their progression through successive changes, 

 until the present state of perfection has been brought about. Life is too short 

 to study the changes brought about by the lapse of countless ages. Mountains 

 have been elevated, valleys hewn out, chasms drilled through the hearts of 

 mountains and many other grand phenomena. The early geologists divided the 

 world's history into distinct periods, supposing that at stated times whole gen- 

 era were swept from the face of the earth, and new ones created. 



These periods have been divided into Faiceozoic or ancient life ; Mesozoic or 

 middle life, and Cenozoic or recent life. The first period in Palceozoic time is the 

 Silurian or age of mollusks, and the enormous belts of limestone laid down attest 

 to the abundant shell-life of the period. This v/as followed by the Devonian or 

 age of fishes. They were all cartilaginous, and but few of their remains are 

 preserved, the Lepidosieus, resembling our common gar-pike, then appeared, as 

 well as sharks and rays. The last period in Palceozoic time is the carboniferous 

 or age of coal plants. The air was dense with carbonic acid, and the luxuriant 

 plant-life cleared the air of this poisonous gas, and stored it away in the great 

 coal fields. Among the plants were the Sigillaria, Tree Fern, Horse-tail, Cycads, 

 etc. The ground, and fallen wood, was covered with sponge-moss. At times 

 the sea came in and covered the organic mass with sand, or mud. The rulers of 

 the estuaries were great placoderms. They were clad in armour of bony plates, 

 resembling shields and bucklers. Sharks and rays, with huge frog-like batrachians, 

 were abundant. At the close of Falceozoic time Cenozoic, the age of reptiles, 

 began. The first period is called Jurrassic, from the Jura Mountains. Here 

 both on land and sea, enormous reptiles reigned supreme, and America has 

 furnished some world-renowned monsters. In the Rocky Mountains, for a num- 

 ber of years, large bones have been found. People supposed them to be frag- 

 ments of fossil wood. 



In 1877 Professors Marsh and Cope made important discoveries, and pub- 

 lished the results of their labors, thus adding another chapter to American palaeon- 

 tology. These were the largest known land animals and are called Dinosaurs. 

 The larger ones reached a height of twenty-five feet and sixty feet in length. 

 They were plant-eaters and fed on the leaves and tender branches of the luxuriant 

 forests through which they wandered. The carnivores or flesh-eaters were smaller 

 and more elegantly built for springing on the clumsy herbivores. They had on 

 each jaw a single row of recurved, serrated teeth. The plant-eaters had several 



