It seems a contradiction to say, that, though these Crinoids were the only representatives of their Class in the early geological ages, while it includes five Orders at the present time, Echinoderms were as numerous and various then as now. But, paradoxical as it may seem, this is nevertheless true, not only for this Class, but for many others in the Animal Kingdom. The same numerical proportions, the same richness and vividness of conception were manifested in the early creation as now; and though many of the groups were wanting that are most prominent in modern geological periods, those that existed were expressed in such endless variety that the Animal Kingdom seems to have been as full then as it is to-day. The Class of the Echinoderms is one of the most remarkable instances of this. In the Silurian period, the Crinoids stood alone; there were neither Ophiurans, Asteroids, Echinoids, nor Holothurians; and yet in one single locality, Lockport, in the State of New York, over an area of not more than a few square miles, where the Silurian deposits have been carefully examined, there have been found more different Species of Echinoderms than are living now along our whole Atlantic coast from Maine to Florida. There is nothing more striking in these early populations of the earth than the richness of the types. It would seem as if, before the world was prepared for the manifold existences that find their home here now, when organic life was limited by the absence of many of the present physical conditions, the whole wealth of the Creative Thought lavished itself upon the forms already introduced upon the globe. After thirty years' study of the fossil Crinoids, I am every day astonished by some new evidence of the ingenuity, the invention, the skill, if I may so speak, shown in varying this single pattern of animal life. When one has become, by long study of Nature, in some sense intimate with the animal creation, it is impossible not to recognize in it the immediate action of thought, and even to specialize the intellectual faculties it reveals. It speaks of an infinite power of combination and analysis, of reminiscence and prophecy, of that which has been in eternal harmony with that which is to be; and while we stand in reverence before the grandeur of the Creative Conception as a whole, there breaks from it such lightness of fancy, such richness of invention, such variety and vividness of color, nay, even the ripple of mirthfulness,--for Nature has its humorous side also,--that we lose our grasp of its completeness in wonder at its details, and our sense of its unity is clouded by its marvellous fertility. There may seem to be an irreverence in thus characterizing the Creative Thought by epithets which we derive from the exercise of our own mental faculties; but it is nevertheless true, that, the nearer we come to Nature, the more does it seem to us that all our intellectual endowments are merely the echo of the Almighty