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Show 50 THE PAST CONDITION A the mammalia and birds there are the rest. mong . none ex t1. nc t ; b n t wllen we come to the reptiles there . most wonderful thing: out of the eight orders, or IS a . thereabouts which you can make among repti 1e s, one-half are ex;inct. These diagrams of the plesiosaurus, the ichthyosaurus, the pterodactyle, give you a notion of some of these extinct reptiles. And here is a cast of the pterodactyle and bones of the ichthyosaurus and the plesiosaurus, just as fresh as if it had been recently dug up in a churchyard. Thus, in the reptile class, there are no less than half of the orders which are absolutely extinct. If we turn to the Amphibia, there was one extinct order, the Labyrinthodonts, typified by the laro-e salamander-like beast shown in this diagram. b No order of fishes is known to be extinct. Every fish that we find in the strata-to which I have been referring-can be identified and placed in one of the orders which exist at the present day. There is not known to be a single ordinal form of insect extinct. rrhere are only two orders extinct among the Crustacea. There is not known to be an extinct order of these creatures, the parasitic and other worms; but there nre two, not to say three, absolutely extinct orders of this class, the Echinodermata; out of all the orders of the Cmlenterata and Protozoa only one, the Rugose Corals. So that, you see, out of somewhere about 120 orders of animals, taking them altogether, you will not, at the outside estimate, find above ten or a dozen extinct. Summing up all the order of animals which have left remains behind them, you will not find above ten or a dozen which cannot be arranged with those of the OF ORGANIC NATURE. 51 present day; that is to say, that the difference does not amount to much more than ten per cent.: and the proportion of extinct orders of plants is still smaller. I think that that is a very astounding, a most astonishing fact, seeing the enormous epochs of time which have elapsed during the constitution of the surface of the earth as it at present exists; it is, indeed, a most astounding thing that the proportion of extinct ordinal types should be so exceedingly small. But now, there is another point of view in which we must look at this past creation. Suppose that we were to sink a vertical pit through the floor beneath us, and that I could succeed in making a section right through in the direction of New Zealand, I should find in each of the different beds through which I passed the remains of animals which I should find in that stratum and not in the others. First, I should come upon beds of gravel or drift containing the bones of large animals, such as the elephant, rhinoceros, and cave tiger. Rather curious things to fall across in Piccadilly ! If I should dig lower still, I should come upon a bed of what we caH the London clay, and in this, as you will see in our galleries up-stairs, are found remains of strange cattle, remains of turtles, palms, and large tropical fruits; with shellfish such as you see the like of now only in tropical regions. If I went below that, I should come upon the chalk, and there I should find something altogether different, the remains of ichthyosauri and pterodactyles, and ammonites, and so forth. I do not . know what Mr. Godwin Austin would say comes next, but probably rocks containing more ammo- |