148 THE PERMO-CARBONIFEROUS RED BEDS OF 



hiding, searching creatures. The harmless Dissorophus, Cacops, Seymouria, 

 and diadcctids scratched and grubbed among the leaves and in the soft earth 

 after worms, larvas, and small creatures of all kinds, or at the water's edge 

 overturned stones and tore apart the rotting stumps of the great lycopods in 

 the same search. Some of these forms were undoubtedly very sluggish and 

 sought their food or endured their fate with an equal stolidity, but others 

 were alert, and on the approach of some carnivorous reptiles there was a 

 sudden dash for the water. Scrambling throvigh the weeds, slipping from 

 convenient logs or stones where they had been sunning themselves, seeking 

 the deep water in the quickest way, the smaller creatures fled the larger ones. 



The terror of those banks must have been the great Dimctrodon. With 

 speed, power, and an armatiu-e of teeth far ahead of any creature of its time, 

 its progress must have been one of devastation. Fearing only individuals of 

 its own kind, the only need for care in its motion was to avoid disturbing the 

 prey before it was sufficiently close to warrant the last dash. When once the 

 great teeth had seized the animal there was no escape. Clepsydrops, in the 

 water or always near it, and Dimctrodon, haunting the higher land or the 

 water's edge, were the tigers of their time. There must have been some nota- 

 ble battles in those woods. The skeletons of Dimetrodon very frequently 

 show the marks of fracture and healing in the slender spines, undoubtedly 

 the results of sanguinary conflicts over victims or for mates. 



On the higher lands, on the banks of the pools, perhaps even upon the 

 shores of the invading seas, the diadcctids, £Ja^/zo.w//r//5, and Pantylus sought 

 the hard-shelled molluscs and other animals, or the vegetation which served 

 them as food. That Diadectes, at least, was not free from attack, is shown by 

 the beginnings of a defensive armor. Edaphosaurus, if the author's ideas are 

 correct, had found some form of protection or isolation which permitted it to 

 develop in comparative peace and safety. 



Among the trees and bushes moved Arcoscelis, undoubtedly with many 

 accompanying forms of which we have no knowledge. 



The composition of the complex fauna undoubtedly changed with the 

 changing climate. Periods of drought would drive some of them out, or 

 cause the death of large numbers which .sought shelter in the desiccating 

 pools. Recurring humidity brought back the life again. The passage of 

 years also brought its changes. Forms familiar in the lower beds are absent 

 above, and new forms come in. It is probable that this was, in part, due to 

 the extinction of old forms and the evolution of new, but there can be no 

 doubt that the conditions during Clear Fork time were decidedly different 

 from those of the Wichita, and the altered composition of a fauna is as 

 frequently the result of migrations as it is of evolution. 



Another thing that must be constantly kept in mind is that the remains 

 are not fotind in their natural habitat. In only a few cases can it be shown 

 that the animals have been buried near where they lived or died. Rivers or 

 currents in larger bodies of water have borne the carcasses away after death, 



