a portion, and often a considerable one, of the accompanying fossil quadrupeds belongs to extinct species. Cases will occur where it may be scarcely possible to draw the line of demarcation between the Newer Pliocene and Pleistocene, or between the latter and the recent deposits; and we must expect these difficulties to increase rather than diminish with every advance in our knowledge, and in proportion as gaps are filled up in the series of geological records. The annexed tabular view (Table 1/1) of the whole series of fossiliferous strata will enable the reader to see at a glance the chronological relation of the Recent and Pleistocene to the antecedent periods. [2] TABLE 1/1. STRATIFIED ROCKS. KAINOZOIC OR TERTIARY: Pleistocene and Recent. Pliocene. Miocene. Oligocene. Eocene. MESOZOIC OR SECONDARY: Cretaceous. Jurassic. Triassic. PALAEOZOIC OR PRIMARY: Permian. Carboniferous. Devonian or old Red Sandstone. Silurian. Ordovician. Cambrian. PRECAMBRIAN OR ARCHAEAN. CHAPTER 2. -- RECENT PERIOD--DANISH PEAT AND SHELL MOUNDS--SWISS LAKE-DWELLINGS. [Illustration: PLATE 1. A VILLAGE BUILT ON PILES IN A SWISS LAKE] (Restored by Dr. F. Keller, partly from Dumont D'Urville's Sketch of similar habitations in New Guinea.) Works of Art in Danish Peat-Mosses. Remains of three Periods of Vegetation in the Peat. Ages of Stone, Bronze, and Iron. Shell-Mounds or ancient Refuse-Heaps of the Danish Islands. Change in geographical Distribution of Marine Mollusca since their Origin. Embedded Remains of Mammalia of Recent Species. Human Skulls of the same Period. Swiss Lake-Dwellings built on Piles. Stone and Bronze Implements found in them. Fossil Cereals and other Plants. Remains of Mammalia, wild and domesticated. No extinct Species. Chronological Computations of the Date of the Bronze and Stone Periods in Switzerland. Lake-Dwellings, or artificial Islands called "Crannoges," in Ireland. WORKS OF ART IN DANISH PEAT. When treating in the "Principles of Geology" of the changes of the earth which have taken place in comparatively modern times, I have spoken of the embedding of organic bodies and human remains in peat, and explained under what conditions the growth of that vegetable substance is going on in northern and humid climates. Of late years, since I first alluded to the subject, more extensive investigations have been made into the history of the Danish peat-mosses. Of the results of these inquiries I shall give a brief abstract in the present chapter, that we may afterwards compare them with deposits of older date, which throw light on the antiquity of the human race.