None of the fishes which are common in our seas at the present day are ever found as fossils in rocks as old as the Orcadian flagstones. The water of the Orcadian lake was fresh water. We know this because we find no marine shells, and no crabs or cuttle-fishes in the flagstones, though these kinds of animals peopled the sea at that time, and would have been preserved as fossils if they had inhabited the lake. Some of the fishes in the lake were very grotesque and oddly-shaped creatures. One of them had two curious bony arms or wings which stuck out from its sides. It is not very common in Orkney, but is sometimes found in quarries near Stromness, and a smaller fish of much the same shape may be got in Deerness occasionally. They are called “winged fishes,” and are quite unlike any fishes now living. So strange is this fossil that when first found it was thought to be a curious beetle. Another strange fish was of great size; its head bones are a foot or more in length. Pieces of the head of this fish may be seen in many parts of Orkney, but the bones of the body were soft and rotted away after the fish died. The back of its head was somewhat like a shovel in shape, and the bones are often half an inch in thickness. There were two great holes for the eyes near the corners of this shield. The back of the neck was protected by another large plate. A specimen of this fossil can be seen in the Stromness museum; it was called by Hugh Miller the _Asterolepis_, or “star-scale fish,” of Stromness. Besides the fishes, other fossils occur in the flagstones, but not of many kinds. At Pickaquoy, near Kirkwall, and in several other places, very small shells, like tiny mussel shells, often cover the surface of the beds of rock. Pieces of wood may also be seen in the flagstones; they are flattened out and form black strips of a coaly substance, but as they must have drifted a long distance from land, and sunk to the bottom only when they became water-logged, they do not tell us much about the nature of the plants which clothed the islands and the shores of the lake. Yet we know that there were no flowers then, no grasses, or sedges, or trees like those that now live, but only great reeds and tree-like plants belonging to the same groups as the horse-tail that grows in watery places and along roadsides, and the little green scaly club moss that creeps through the heather, sending up its fruit-bearing spikes. There were also many kinds of ferns. In the forests and swamps there were land-snails and insects, but no frogs or lizards, still less any birds or other warm-blooded creatures. The fishes are the highest types that then existed; they were the “lords of creation” in that day. [Illustration: _“Winged fish” (Pterichthys)._] A PEAT-MOSS.