for they recall the past, as the former anticipate the future.  And it is not only among the Fishes and the Reptiles that we find these combinations.  The most numerous of the ancient Radiates are the Acalephlan Corals, combining, in the Hydroid form, the Polyp-like mode of life, habits, and general appearance with the structure of Acalephs.  The Crinoids, with the closed cups in some, and the open, star-like crowns in others, unite features of the present Star-Fishes and Sea-Urchins, and, by their stem attaching them to the ground, include also a Polyp-like character; while the Trilobites, with their uniform rings and their prominent anterior shield, unite characters of Worms and Crustacea.

These early types seem to sketch in broad, general characters the Creative purpose, and to include in the first average expression of the plan all its structural possibilities.  The Crinoid forms include the thought of the modern Star-Fishes and Sea-Urchins; the simple chambered shells of the Silurian anticipate the more complicated structure of the later ones; the Trilobites give the most comprehensive expression of the Articulate type; while the early Fishes not only prophesy the Reptiles which are to come, but also hint at Birds and even at Mammalia by their embryonic development and their mode of reproduction.

Looked at from this point of view, the animal world is an intellectual Creation, complete in all its parts, and coherent throughout; and when we find, that, although these ancient types have become obsolete and been replaced by modern ones, yet there are always a few old-fashioned individuals, left behind, as it were, to give the key to the history of their race, as the Gar-Pike, for instance, to explain the ancient Fishes, the Millepore to explain the old Acalephian Corals, the Nautilus to be the modern exponent of the Ammonites and Orthoceratites of past times, we cannot avoid the impression that this Creative work has been intended also to be educational for Man, and to teach him his own relation to the organic world.  The embryology of the modern types confirms this idea, for here we find an epitome of their geological history.  The embryo of the present Star-Fishes recalls the Crinoids; the embryo of the Crab recalls the Trilobites; the embryo of the Vertebrates, including even that of the higher Mammalia, recalls the ancient Fishes.  Does not this fact, that the individual animal in its growth recalls the history of its type, prove that the Creative Thought in its immediate present action embraces all that has gone before, as its first organic expression included all that was to come?  The study of Nature in its highest meaning shows us the present doubly rich with all the past, and the past linked and interwoven with the present, not lying divorced and dead behind it.