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Show . . 66 ERA OF THE TERTIARY FORMATION.- 1\l!AYMALIA ABUNDANT. THE chalk-beds are the highest which extend over a considerable space; but in hollows of thes:e beds, c~~pa i ratively limited in extent, there have been f?rmed ~ell~~ h strata~clays, linlestones, marls, a~ternahng-to w 1 .1Cd the name of the Tertia'r!J Format~on has b~en app ~e • London and Pal'is alike rest on basins of thu~ f?r-rnatwn., and another such basin extends from near W Inch~stei! under Southampton, and re-appears in the I.sle ~f Wight. There is a patch or fragment of the forn1ahon 1n one of the Hebrides. A stripe of it extends along the .east coa~t of North America, from Massac~usett~ to Flonda. I~ IS also found in Sicily and Italy, Insensibly bl.ended with fmtmations still in progress. Th~ugh comparatively a local formation,. it is not of the le~ 1mportan?e as ~ record ?f the condition of the earth dunng a certain p~nod. As I.n other formations ' it is ma.r ked, in. the most d1stant locah- ties by identity of organic remams. The hollows filled by the tertiary formation must. b considered as the beds of estuaries left at the concluswn of the cretaceous period. We have seen that an estuary, either by the drifting up of its nwuth, or a change o~ level in that quarter, may be supposed to have become an Inland sheet of water, and that by another change, of the reve~·se kind, it may be supposed to have become an estuary again. Such chancres the Paris basin appears to have undergone oftener th~n once, for, first, we have there a fresh .. w~ter formation of clay and limestone beds; then, a rnannelimestone formation; next, a second fresh-water fonnation in which the material of the celebrated 1Jlaster of .. Paris (gypsum) is inc_luded; then, a second m~rine f?rmation of sandy and hmy beds; and ~nally, a thn:d sene~ of fresh-water strata. Such alternatiOns occur In othei examples of the tertiary formation likewi~e. The tertiary beds present all but an entirely new set of a~nmals, and as we a.scend ~n the se.rie~, ~e fin~ !?ore and more of these idenbcal with species still existing upon earth. a~ if we had now reached the dawn of the present state of the zoology of our planet. By the study of the shells alone, Mr. Lyell has been enabled to divide the whole term into four sub-periods, to which he has given ERA OF THE TERTIARY FORMATION. 67 name~ with referenc~ to t~~ proportions which they respech vely present ol survIVIng species-first the eocene (irorn 'r;wr, the dawn; xawor, reeent ;). second the nlio~ ene (uelwv, less:) third older pliocene ( 1rAelc.>v more·) 'ourth, newer pliocene. ' , .EOCENE SUB-PERIOD. The eoc.ene I?eriod presents, in three continer:tal groups, 1238 spe?Ies of shells, of which forty-two, or 3.5 per cent., yet iloun~h. ~orne of these are remarkable enough ; but they ~ll Sin}~ Into insignificance beside the man1ma.lian r~mains WhiCh the lower eocene deposits of th~ Pari~ ba- 1 n present to, us, showing that the land had now beet) me tb~ theatre ot ~n e~tensive creation of the highest clac;:s of animals. Cuvier.ascertai~ed about .fifty species of t!10se, all of them long su1ce extinct. A considerable number are pachyderr_nata, * ?f a. character approximating to the South .Amencan tapir: the names palreotherium, antbJ:aco~ henum, anop.lotberium., lop~iodon, &c., have been appl~ ed to them With a considerat1on ·of more or less conspicuous peculiarities ; but a description of the first may g.Ive some general Idea of the whole. It \Vas about thE) SI.ze of a horse, but more squat and clumsy, and \Vith a hea .. VIer head, .and a lower jaw shorter than the upper; the feet, also, Instead of hooves, presented three leu o·e toes rounded., and unprovided with claws. These anim~ls wer~ all h.erbivorous. Amougst an immense number of others ~re 1ound many new reptiles, some of them adapted for fresh wa~er; species of birds allied to the sea-lark, curJew, quail, buzzard, owl, and pelican; species allied to t.he dormouse ~nd sg uirrel ; also the opossum and racoon; and s_recies allied to the genette, fox, and wolf. MIOCENE SUB-PERIOD. In the ~io?eno sub: period, t.he shells give eighteen per ~~nt. of existing. species, showing a considerable advance hom the ~~eceding era,. with respect to the inhabitants of the sea. ll~e advance In the land animals is less marked but yet considerable. The predominating forms are stili t • Thic.k-s~dnne~ animals. This term has been given by Cuvler o :m order m wJuch tl1 • 1 l h t h · mcluded. e lOg, e e11 an , orse, and rhmoceros are |