PRACTICAL STUDIES IN GEOLOGY. . 483 



rows. In the Judith River group the Dinosaurs walked erect ; their front Hmbs 

 were small, and armed with claws for grasping the branches of trees on which they 

 fed. A ponderous tail helped to support their enormous weight. They had three 

 rows of teeth in each jaw, with a magazine below each old tooth, containing five 

 young ones. As fast as one row wore off another took its place. We found 

 thousands of these cast-off crowns. The second period is called the Triassic. 

 Here huge reptiles on sea and land were the ruling types. Some are called 

 Labyrinthodonts from the peculiar manner in which the enamel of the teeth is 

 folded. They were clad in armors of bony plates. Crocodile-like animals, with 

 beautifully sculptured bones were common, as well as sharks, gars, etc. 



In northern Texas the beds are made up chiefly of red clay, which is so 

 finely divided that all the waters flowing from them, hold it in solution. During 

 high water or on windy days, the water is as thick as cream. The next period 

 is the Cretacous when the chalk of England and America was laid down. The 

 first group in the west is called Dakota, by Prof. Hayden. The formation of 

 red-sandstone, and variegated clays, were laid, down in an open sea dotted here 

 and there with islands. The formation enters Kansas near the mouth of Cow 

 Creek, extending in a northeasterly direction through the State, Nebraska, Min- 

 nesota, British America and so on to Greenland. The trees, like those in our 

 existing forests, then appeared. Here flourished the magnificent Red-wood, 

 Catalpa, Menispermites, Tulip-tree, Cinnamon, Fig, Sassafras, etc. They left 

 impressions in the sandstone of Kansas and Nebraska, and some two hundred 

 species have been described by the noted palseontologist Prof. E. Lesquereux, of 

 Columbus, Ohio. 



During the Niobrara group great beds of chalk and blue shale, were laid 

 down in western Kansas. Here appeared the first bony and edible fishes : For- 

 theus Molossus, Cope, reached a length of twenty feet. It had a large bull-dog- 

 shaped head with fangs projecting four inches from the mouth. It had another 

 weapon of offense and defense in the shape of pectoral and dorsal fins, three feet 

 long. In some species, one edge is serrated, and even in their fossil form are 

 hard enough to be used for splitting wood. Another peculiar species was Cope's 

 Erysidhes or snout fish. It used this weapon as a modern sword-fish does its 

 sword. But the rulers of the deep open sea were the Saurians or sea-serpents. 

 Cope's Liodo7i poriges reached a length of eighty feet. It had four powerful pad- 

 dles, which by the aid of a long eel like tail enabled it to go through the water at 

 great speed. Its weapon of offense was a long bony snout, that was used as a 

 battering-ram. 



Clidasies tortor, Cope, was a small animal, about forty feet in length. It was 

 provided with an additional set of articulations in the vertebrae to enable it to 

 coil up, like a snake. Marsh's Clidastes pumulus was only twelve feet long, and 

 doubtless often fell a victim to the sharks and other rapacious fishes that abounded 

 in these waters. One peculiarity of these Saurians was that they had no expansi- 

 ble gullet, as in modern serpents; another method was given them in the shape 

 of hinges of the ball and socket pattern just back of the dentry-bone. This en- 



