guished by the double row of small spines running down the central lobe, and which give to it a more Cyathophyllum hexagonum. "trilobed' appearance than any other species in the whole family. But, clear though the sea-water generally was in which these Devonian beds were formed, every now and then shifting currents brought fine mud and other sediments. These were thrown down on the ocean-floor, where they alternated with the bands of limestone. Eventually, the sea again maintained its purity for a long period, during which the corals and other clear-water-loving animals resumed their avocations, and left behind them traces of their work. I have said that where Ireland now stands, was part of a great continent, or some other extension of dry land, towards the close of the age in which I was born. Of this I cannot speak with certainty; but the evidence is strongly in favour of the idea. In the country of Kilkenny are a series of finegrained greenish sandstones, regularly bedded; they are full of evidences of fresh-water deposition. Nowhere, in Europe at least, will you met with such well-preserved land-plants; all of which prove, by the perfect manner in which they have been preserved, that they could not have been drifted from a distance, or been in the water long. Among the most attractive of these remains are those of a treefern, formerly called Cyclopteris, or "Round-leaved Fern," but now named Palæopteris Hibernicus, or the "Primitive Irish Fern." Nothing could be more exquisite than this beautiful fern, even in a fossil state, and you may therefore guess how attractive were its groves when it was the monarch of the primeval forests, and its graceful fronds bent over the clear waters of a lake which equalled in picturesqueness those of the Emerald Island of these times. This fern is not unlike, in general appearance, the modern "Royal Fern" (Osmunda regalis), with the exception that it has no mid-rib-its veins ramifying from the base towards the exterior of the leaf. Associated with this tree-fern were great and small club-mosses, which trailed over the ground, and formed a rich green carpet of various tints. Among the commoner of these extinct club-mosses were Sagenaria (of which the seed-vessels and catkins are well preserved); Psilophyton, a simpler clubmoss, and the larger and more tree-like Lepidodendron, which afterwards became so abundant during the Carboniferous epoch. Besides these we have evidences of other kinds of vegetation, and there is no doubt that the higher grounds were more or less covered with more highlydeveloped and organized species. What is further corroborative of the fresh-water origin of the Irish sandstones is the immense number of bivalve shells, exactly resembling the large fresh-water mussels (Anodon) which abound in modern English rivers. Both in appearance and structure these fossil shells are evidently closely allied, and therefore they are called Anodonta. They abound by thousands in some parts of the sandstones, associated with plantremains, and with those of crustaceans which seem allied to the modern crayfish. So long did these large Irish lakes exist, that mud was strewn along their bottoms which ultimately formed rock several hundred feet in thickness. I am told that similar deposits of fine mud and shell marl are now going on along the floors of the forest-fringed lakes of North America. Change the character of the vegetation there, and you have no indistinct restoration of the Irish Devonian lakes. Many of the fish would do; for the "bony pike," a ganoid fish, still lives there, associated with colonies of "swan mussels" (Anodon) clustering on the bottom. So much for the brief outlines of my story. Much more could be said upon this remarkable epoch; but if I have given anything like an idea of my origin and of the character of the life-forms with which I was brought into contact, my business is done, and I accordingly retire for another geological speaker. |