I here present one of our common Horse-Shoe Crabs above one of these old-world Crustaceans, and it will be seen, that, while the latter preserves some of the Trilobitic characters, such as the marked articulations on the posterior part of the body and their division into three lobes, yet in the prominence of its anterior shield, its more elongated form, and tapering extremity, it resembles its modern representative. In some of them, however, there is no such sharp point as is here figured, and the body terminates bluntly. There were a large number of these Entomostraca in the Carboniferous period, a group which is chiefly represented among living Crustacea by an exceedingly minute kind of Shrimp; but in those days they were of the size of our Crabs and Lobsters, or even larger, and the Horse-Shoe Crab still maintains their claim to a place among the larger and more conspicuous members of the class. The Insects were few, and, as I have said above, of a kind which seeks a moist atmosphere, or whose larvae live altogether in water. They are not usually well preserved, as will be seen from the broken character of the one here represented, although the wood-cut is made from a better specimen than is often found. We have, however, remains enough to establish unquestionably the fact of their existence in the Carboniferous period, and to show us that the type of Articulates was already represented by all its classes. [Illustration] Not so with the Vertebrates. Fishes abound, but their class still consists, as before, of the Ganoids, those fishes of the earlier periods built on the Gar-Pike and Sturgeon pattern, and the Selachians, represented now by Sharks and Skates. In the Carboniferous period we begin to find perfectly preserved specimens of the Ganoids, and the adjoining wood-cut represents such a one. Of the old type of Selachians we have again one lingering representative in our own times to give us the clue to its ancestors,--as the Gar-Pike explains the old Ganoids, and the Chambered Nautilus helps us to understand the Chambered Shells of past times. The so-called Port-Jackson Shark has features which were very characteristic of the Carboniferous Sharks and are lost in the modern ones, so that it affords us a sort of link, as it were, and a measure of comparison, between those now living and the more ancient forms. It is an interesting fact that this only living representative of the Carboniferous Shark should be found in New Holland, because it is there, in that isolated continent, left apart, as it would seem, for a special purpose, that we find reproduced for us most fully the character of the Animal Kingdom in earlier creations. [Illustration]