In England, the Silurian archipelago, now filled up and occupied by deposits of the Devonian and Carboniferous systems, would be covered with carboniferous vegetation; dry land would now extend, almost without interruption, from Cape Wrath to the Land’s End; but, on its eastern shore, the great mass of the region now lying less than three degrees west of Greenwich would, in a general sense, be under water, or form islands rising out of the sea. Alphonse Esquiros thus eloquently closes the chapter of his work in which he treats of this formation in England: “We have seen seas, vast watery deserts, become populated; we have seen the birth of the first land and its increase; ages succeeding each other, and Nature in its progress advancing among ruins; the ancient inhabitants of the sea, or at least their spoils, have been raised to the summit of lofty mountains. In the midst of these vast cemeteries of the primitive world we have met with the remains of millions of beings; entire species sacrificed to the development of life. Here terminates the first mass of facts constituting the infancy of the British Islands. But great changes are still to produce themselves on this portion of the earth’s surface.” Having thus described the _Primary Epoch_, it may be useful, before entering on what is termed by geologists the _Secondary Epoch_, to glance backwards at the facts which we have had under consideration. In this Primary period plants and animals appear for the first time upon the surface of the cooling globe. We have said that the seas of the epoch were then dominated by the fishes known as _Ganoids_ (from γανος, _glitter_), from the brilliant polish of the enamelled scales which covered their bodies, sometimes in a very complicated and fantastic manner; the _Trilobites_ are curious Crustaceans, which appear and altogether disappear in the Primary epoch; an immense quantity of Mollusca, Cephalopoda, and Brachiopoda; the _Encrinites_, animals of curious organisation, which form some of the most graceful ornaments of our Palæontological collections. [Illustration: Fig. 77.--Lithostrotion. (Fossil Coral.)] But, among all these beings, those which prevailed--those which were truly the kings of the organic world--were the Fishes, and, above all, the _Ganoids_, which have left no animated being behind them of similar organisation. Furnished with a sort of defensive armour, they seem to have received from Nature this means of protection to ensure their existence, and permit them to triumph over all the influences which threatened them with destruction in the seas of the ancient world. [Illustration: Fig. 78.--Rhyncholites, upper, side, and internal views. 1, Side view (Muschelkalk of Luneville); 2, Upper view (same locality); 3, Upper view (Lias of Lyme Regis); 4, Calcareous point of an under mandible, internal view, from Luneville. (Buckland.)]