the first dawn of life has ever been an onward one, as regards the development not only of organic structure but of the social relations; and if it be true that physical organization finds its archetype in man, it is assuredly no less so that in him too we meet with the highest manifestation of those instincts which, by linking individual to individual, have ever marked out the vertebrate tribes of animals from the more machine-like characteristics of the invertebrate. We pass now to the vertebrate animals, and shall look for a little into the general grade and organization of the fishes that characterized the carboniferous rivers and seas. A collection of the ichthyolites of the carboniferous rocks presents almost every variety in the mode of preservation. The smaller species are frequently found entire, and show their shining scales still regularly imbricated as when the creatures were alive. The larger forms seldom occur in other than a very fragmentary condition. The limestones yield dark-brown or black, oblong, leech-like teeth, which are found on examination to be those of an ancient family of sharks. The shales are often sprinkled over with glittering scales and enamelled bones. Some of the coals and ironstones yield in abundance long sculptured spines, huge jaws bristling with sharp conical teeth, and detached tusks, sometimes five or six inches long. In short, the naturalist who would decipher the ichthyology of the Coal formation, finds before him, in the rocks, not a suite of correctly arranged, and carefully preserved skeletons, but a set of disjointed, unconnected bones; here a tooth, there a scale, now a jaw, now a dermal plate, all mingled at random. And yet, though the evidence lie in this fragmentary state, our knowledge of these ancient fishes is far from being correspondingly meagre. To such precision has the science of comparative anatomy arrived, that a mere scale or tooth is often enough to indicate the nature and functions of the individual to which it belonged, and to establish the existence in former times of a particular class or order of animals. Thus the smooth rounded teeth of the mountain limestone are found to present both externally and internally a close resemblance to the hinder flat teeth of the sole living cestraciont (_C. Philippi_); and we hence learn that a family of sharks, now all but extinct, abounded in the palæozoic seas. The occurrence of a set of dark, rounded little objects, which by the unpractised eye would be apt to be mistaken for pebbles, is in this way sufficient at once to augment our knowledge of the various animals of the Carboniferous period, and to establish an important fact in the history of creation.