[13] See M. Pictet's "Palæontologie."
An extensive series, comprising many isolated groups of marine and lacustrine deposits, containing fossil remains of animals and vegetables of all classes; the greater number of genera and species in the most ancient or lowermost beds belong to extinct types.
Subdivisions:—
1. The Pliocene[14] (more new, or recent.[15] Wond. p. 221); strata in which the shells are for the most part of recent species, having only about ten per cent of extinct forms. (Norwich Crag.)
2. The Miocene (less recent,[16] Wond. p. 221); containing about 20 per cent of recent species of shells. (Suffolk Crag.)
3. The Eocene (dawn of recent,[17] in allusion to the first appearance of recent species—Wond. p. 226); the most ancient tertiary strata contain but very few existing species of shells; not more than five per cent. (London, Hants, and Paris basins.)
[14] In the present state of our knowledge, this arrangement is of great utility, but it will probably require considerable modification, and must, perhaps, hereafter be abandoned; for it cannot be doubted, that strata in which no recent species have yet been found, may yield them to more accurate and extended observations, and those in which only a few recent species are associated with a large number of extinct forms, may have these proportions reversed.
[15] From πλειων, pleion, more; and καινος, kainos, recent.
[16] From μεἱων, meion, less, and recent.