the dorsal fins of the ancient shark were provided each with a hard, stout spine. The teeth were large, flat and fit for crushing. We know these ancient sharks only by the spines, shagreen tentacles and the teeth. These, however, furnished abundant evidence that the sharks in the upper Silurian were numerous as to individuals and species. The Chimera, a fish much resembling the sharks, was also abundant in the upper Silurian. A group of fishes usually known as ganoids and which comprise the lung fishes of the Nile, of Australia, the garpikes of North America and the sturgeons, were very abundant during the closing days of the Silurian. The fishes of this group are especially well preserved as fossils, their covering consisted of bony plates or bucklers or of scales covered with a coat of enamel. Their outer covering was well suited to become fossilized, and so we know this group much better than we do any other found in the Silurian. The next and last group of fishes is known as Teleosts, or bony fishes. To this group belong our typical fishes, such as black bass, sun fishes, suckers, cat fishes and the like. None of this group lived during the Silurian. [Illustration: HOME OF THE SEA BIRDS. CHICAGO: A. W. MUMFORD PUBLISHER.] Following the Silurian came the Devonian, which is called the age of fishes. In no time in the world's history have fishes been so large and so abundant as during this age. They outclassed in every respect all other animals. The same general types flourished as those which existed in the latter part of the Silurian. There were more species and more individuals and some grew to an enormous size. Fishes ruled the Devonian seas. The crustaceans, such as trilobites which greatly predominated during the Silurian age, diminished greatly during the Devonian. In the struggle for existence they decreased in size and in numbers, and were obliged to seek safety in less favorable places. The Devonian fishes were largely sharks and ganoids, especially the latter. These were covered, with hard, enamel-coated scales or bony plates. Some were short and heavy and entirely encased in a covering of large bony plates. They were evidently anything but pretty and their movements in the water must have been extremely awkward. Others were formed much after our own ideas of fishes. These bore much resemblance to our garpikes, the lung fish of the Nile and the lung fish of Australia, and the worthless dog fish of our own fresh waters. Anglers and fishermen all despise these fishes now, yet in Devonian times the fishes most nearly like them were evidently the most handsome and graceful of all fishes then living. It appears as if fishes in those days did not fight each other. They found abundant sea room and plenty of food in the form of invertebrates. Of course it is quite probable that many fish-like animals existed at this time, but possessing no