The seas of this epoch included an immense number of Zoophytes, nearly 400 species of Mollusca, and a few Crustaceans and Fishes. Among the Fishes, _Psammodus_ and _Coccosteus_, whose massive teeth inserted in the palate were suitable for grinding; and the _Holoptychius_ and _Megalichthys_, are the most important. The Mollusca are chiefly Brachiopods of great size. The _Bellerophon_, whose convoluted shell in some respects resembles the Nautilus of our present seas, but without its chambered shell, were then represented by many species. Crustaceans are rare in the Carboniferous Limestone strata; the genus Phillipsia is the last of the Trilobites, all of which became extinct at the close of this period. As to the Zoophytes, they consist chiefly of Crinoids and Corals. We also have in these rocks many Polyzoa. Among the corals of the period we may include the genera _Lithostrotion_ and _Lonsdalea_. Among the Polyzoa are the genera _Fenestrella_ and _Polypora_. Lastly, to these we may add a group of animals which will play a very important part and become abundantly represented in the beds of later geological periods, but which already abounded in the seas of the Carboniferous period. We speak of the _Foraminifera_, microscopic animals, which clustered either in one body or divided into segments, and covered with a calcareous, many-chambered shell, as _Fusulina cylindrica_. These little creatures, which, during the Jurassic and Cretaceous periods, formed enormous banks and entire masses of rock, began to make their appearance in the period which now engages our attention. This terrestrial period is characterized, in a remarkable manner, by the abundance and strangeness of the vegetation which then covered the islands and continents of the whole globe. Upon all points of the earth, as we have said, this flora presented a striking uniformity. In comparing it with the vegetation of the present day, the learned French botanist, M. Brongniart, who has given particular attention to the flora of the Coal-measures, has arrived at the conclusion that it presented considerable analogy with that of the islands of the equatorial and torrid zone, in which a maritime climate and elevated temperature exist in the highest degree. It is believed that islands were very numerous at this period; that, in short, the dry land formed a sort of vast archipelago upon the general ocean, of no great depth, the islands being connected together and formed into continents as they gradually emerged from the ocean.