. The ancient life-history of the earth; a comprehensive outline of the principles and leading facts of palæontological science. Paleontology. THE EOCENE PERIOD. 291 Many species are known, and they are particularly character- istic of the Middle and Upper of these periods—their place. Fig. 214.—Niimmulina hevigata. Middle Eocene. being sometimes taken by Orbitoides, a form very similar to the Nummulite in external appearance, but differing in its internal details. In the Middle Eocene, the remains of Nummulites are found in vast numbers in a very widely-spread and easily- recognised formation
. The ancient life-history of the earth; a comprehensive outline of the principles and leading facts of palæontological science. Paleontology. THE EOCENE PERIOD. 291 Many species are known, and they are particularly character- istic of the Middle and Upper of these periods—their place. Fig. 214.—Niimmulina hevigata. Middle Eocene. being sometimes taken by Orbitoides, a form very similar to the Nummulite in external appearance, but differing in its internal details. In the Middle Eocene, the remains of Nummulites are found in vast numbers in a very widely-spread and easily- recognised formation known as the " Nummulitic Limestone " (fig. 10). According to Sir Charles Lyell, "the Nummulitic Limestone of the Swiss Alps rises to more than 10,000 feet above the level of the sea, and attains here and in other moun- tain-chains a thickness of several thousand feet. It may be said to play a far more conspicuous part than any other Tertiary group in the solid framework of the earth's crust, whether in Europe, Asia, or Africa. It occurs in Algeria and Morocco, and has been traced from Egypt, where it was largely quarried of old for the building of the Pyramids, into Asia Minor, and across Persia by Bagdad to the mouths of the Indus. It has been observed not only in Cutch, but in the mountain-ranges which separate Scinde from Persia, and which form the passes leading to Cabul; and it has been followed still further east- ward into India, as far as Eastern Bengal and the frontiers of ; The shells of Nummulites have been found at an elevation of 16,500 feet above the level of the sea in Western Thibet; and the distinguished and philosophical geologist just quoted, further remarks, that " when we have once arrived at the conviction that the Nummulitic formation occupies a mid- dle and upper place in the Eocene series, we are struck with the comparatively modern date to which some of the greatest revolutions in the physical geography of Europe,
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