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The other great types of the Animal Kingdom are very fully represented in the Tertiaries, and in their general appearance they approach much more closely those of the present creation than of any previous epochs.  Professor Heer has collected and described the Tertiary Insects in great number and variety; and the Butterflies, Bugs, Flies, Grasshoppers, Dragon-Flies, Beetles, etc., described in his volumes, would hardly be distinguished from our own, except by a practised entomologist.  Among Crustacea, the Shrimp-like forms of the earlier geological epochs have become much less conspicuous, while Crabs and Lobsters are now the prominent representatives of the class.  Among Mollusks, the Chambered Shells, hitherto so numerous, have become, as they now are, very few in comparison with the naked Cephalopods.  The Nautili, however, resemble those now living in the Pacific Ocean; and some fragments of the Paper-Nautilus have been found, showing that this delicate shell was already in existence.  There is one very peculiar type of this class, belonging to the Tertiaries, which should not be passed by unnoticed.  It partakes of the character both of the Cretaceous Belemnites and of the living Cuttle-Fish, and is known as the Spirulirostra.  Another very characteristic group among the Tertiary Shells is that of the Nummulites, formerly placed by naturalists in immediate proximity with the Ammonites, on account of their internal partitions.  This is now admitted to have been an error; their position is not yet fully determined, but they certainly stand very low in the scale, and have no affinity whatever with the Cephalopods.  The subjoined wood-cut represents one of these Shells, so numerous in the Tertiaries that large masses of rock consist of their remains.  The Univalve Shells or Gasteropods of the Tertiaries embraced all the families now living, including land and fresh-water Shells as well as the marine representatives of the type.  Some of the latter, as, for instance, the Cerithium, are accumulated in vast numbers.  The limestone quarries out of which Paris is chiefly built consist wholly of these Shells.  The fresh-water basins were filled with Helices, one of which is represented in the following wood-cut, with Planorbis, Limnaeus and other Shells resembling those now so common in all our lakes and rivers, and differing from the living ones only by slight specific characters.  The Bivalves also have the same resemblance to the present ones, including fresh-water Mussels as well as the marine Clams and Oysters.  Among Radiates, the higher Echini (Sea-Urchins) have become numerous, while the other Echinoderms of all families abound.  Corals include, for the first time, the more highly organized Madrepores.

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In the Tertiaries we see the dawn of the present condition of things, not only in the character of the animals and plants, but in the height of the mountains and in the distribution of land and sea.