OF SOUTH CAROLINA. 53 
Fig. 9. 
1—Granite. 2—Metamorphic rocks. 3—Paleozoic series. 4—Secondary series. 5—Tertiary series, 
Succession of Organic Remains.—We may now take a slight restrospect of the Geological 
succession of organic remains, as developed by Geologists in all parts of the world. Commencing 
with the Potsdam sandstone of New York, which is the oldest fossiliferous rock of this country, 
we find that the first organic forms that occur are those of cellular plants, such as sea-weeds, and a 
small Brachiopodous mollusc, the Lingula. As we ascend in the Silurian series, corals and Crinoidea 
make their appearance in vast numbers, and the Brachiopods of various genera multiply. 
The sub-kingdom Articulata is represented by numerous 'Trilobites, and the Cephalopodous mol- 
lusus by species having chambered shells. 
Remains of fishes are found in the Silurian rocks of Europe, but they are exclusively those of 
the cartilaginous family ; and no perfect forms occur till we reach the Old Red. 
Towards the Upper part of the Silurian rocks of New York, plants that indicate the existence of 
dry land appear for the first time. 
During the Carboniferous period plants seem to have attained the greatest development, and two 
species of Poa, the only fossil grasses known, are found in the coal formation of England; and, 
what is equally curious, the first insect appears here. 
The Trilobites disappear altogether with the carboniferous rocks, while voracious fishes, of great 
size, inhabited the seas throughout the entire period. 
In the Magnesian limestone remains of reptiles are found for the first time. 
In the New Red we find the earliest evidences of the existence of birds; and, in Europe, Batra- 
chian reptiles have left their tracks and some bones in this formation. 
In the Lias and Oolite the class Reptilia is represented by the most extraordinary forms. The 
Enaliosauria of this period have left behind them no representatives, unless the “ Sea-serpent” 
should turn out to be a veritable inhabitant of our seas. Jn the Oolite we find the first mammalian 
remains, the jaw of an Opossum. 
The noble tree-ferns of the Carboniferous period have disappeared, and a few palms are found 
lingering behind. Insects are now, for the first time, abundant; and in the Wealden formation the 
remains of lizards of enormous proportions exist. 
In the Cretaceous system some remains of the Saurians of the preceding groups are found, but 
the most remarkable reptile peculiar to this period, is the Mosasaurus. 
Cartilaginous fishes, of the Shark and Ray tribes, are numerous, but the fierce Ganoids begin to 
give place to the Ctenoids and Cycloids, which make their first appearance here. With the excep- 
tion of two genera, the existence of the Ganoids terminates with the Cretaceous system, and, 
with a solitary exception, the Cephalapods disappear altogether with these rocks. 
id 
