SILLIMAN'S INTRODUCTION. 19 



Vegetation of the Coal 'period. — The most exuberant vegetation 

 appears to have been that of the coal period, and its entombed trea- 

 sures now supply the world with fuel, especially in countries where 

 the forests are exhausted, or where economy of the modern vege- 

 tation, or preference for the results of the ancient, decides the 

 choice. 



Varieties of the Ancient Fossil Vegetation. — The ancient vegetation 

 appears in many forms, as in that of lignite, of coal, and of siliceous, 

 calcareous, and ferruginous petrifactions, still preserving the pecu- 

 liar structure ; and this has been made still more distinct and satis- 

 factory, by cutting thin slices of the petrified trunks, and grinding 

 them down until they become transparent, when the microscope 

 reveals the internal structure, which characterizes the family. Thus, 

 ifc has been made to appear, that coniferous trees of forest growth, 

 occur in the coal formation in the south of Scotland, and the north 

 of England ; and that zamias and other palm-like trees were coeval 

 with the chalk in the south of England. But no species of the 

 ancient world are identical with any of the modern, and the early 

 vegetation implies, generally, a warm and moist climate, and great 

 fertility of production. 



Aquatic Animals. — Reptiles. — The abundance of remains of 

 animals, almost exclusively of marine species, attests the great pre- 

 valence of the ocean in the earlier geological periods, and it is not 

 until we have passed the coal in the ascending order, that we begin 

 to find reptiles of marine or of amphibious families, and ultimately, 

 still higher up, of terrestrial races. With a similarity of type to 

 the families of the present day, both the genera and species are, 

 however, with but very few exceptions, extinct. Some were car- 

 nivorous and swam in the shallow seas, estuaries, lagoons, and bays, 

 and preyed upon fishes, molluscous animals, and each other ; 

 some lived on land and were herbivorous ; a few genera, the 

 megalosaurus and iguanodon, for example, were colossal in size, 

 and terrible in form, but it is probable that the latter of these 

 terrestrial saurians was harmless and inoffensive, while the tooth of 

 the megalosaurus would indicate a carnivorous animal, like the marine 

 saurians. Bones of many genera and species of the reptile tribes, 

 especially the saurians, have been found, and of some individuals, 

 entire, or nearly perfect skeletons ; — among them, several of vast 

 dimensions have been discovered enclosed in the solid rocks,, 



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