It is only within recent years that the researches more especially of Barrande, Hicks, Lapworth, Linarrson, Brögger, and others in Europe, and of Matthew, Ford and Walcott in America, have enlarged the known animals of the Lower Cambrian to nearly 200 species, and below this we know as yet very little of animal life. We may therefore take the Lower Cambrian, or "Olenellus Zone" as it has been called from one of its more important crustaceans,[3] as our starting-point for plunging into the depths below. In doing so, we may remark on the orderly and symmetrical nature of the chain of life, and on the strange fact that for so long ages animal life seems to have been confined to the waters, and to have undergone little development toward its higher forms. It is like a tree with a tall branchless stem bearing all its leaves and verdure at the top, or like some obscure tribe of men long living in isolation and unknown to fame, and then, under some hidden impulse or opportunity, becoming a great conquering and dominant nation. Or to compare it with higher things, it is like the Christian religion, for ages confined to a small and comparatively unimportant people, and developing slowly its faith and hopes, and then suddenly, under the personal influence of Christ and His apostles, spreading itself over the world, and in a few centuries becoming the ruling power in its greatest empire, surviving the fall of this and permeating all the great nations that sprang from its ruins. God's plans in nature, in history, and in grace seem to us very slow in their growth and maturity, but they are very sure. [Footnote 3: See figure, p. 20.] _LIFE IN THE EARLY CAMBRIAN_ II _LIFE IN THE EARLY CAMBRIAN_ In the old Chaldean fable of the descent of Ishtar into Hades, to recover her lost Tammuz, at each successive gate of the lower regions she is stripped of some of her ornaments and garments, till at length she has to appear naked and unadorned in the presence of the lord of the Nether World. So in our descent from the surface on which men live, through the successive rocky layers of the earth's crust, we leave behind, one by one, all the higher forms of life with which we are familiar; but there still remain to us our six groups of aquatic invertebrates, in the guise, it is true, of species and genera now unknown in a living state, yet well represented as far down as the lower part of the Cambrian. Let us now suppose that we take our stand on the shores of the Cambrian sea, or cast our dredge into its waters in search of these old animals; though we can only actually do so by painfully hammering and chiselling them out of their rocky tombs, and this often in fragments which must be put together before we can fully realize the forms and structures of the animals to which they belonged.