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Show ERA OF THE OOLITE ~tnimal havino- a foot fifteen inches in ler,gth (one-haU more ti1an that of the ostrich ) and a stride of fi·orn tour •o six feet, has been appropriately entitled, ornithichnite.fl giganteu,s. ERA OF TiiE OOLITE. COMMENCEMENT OF MAMMALIA. THE chronicles of this period consist of a series of beds, mostly calcareous, taking their general name ( Oolit~ SysteJn) frorn a conspicuous member yf them-the oohte-:-a limestone composed of an aggregation of small round grains or spherules, and so called from its fancied resemblance to a cluster of egrrs. or the roe of a fish. This texture of stone is novel a~d striking. It is supposed to be of chemical origin, each spherule being an aggregation of particles round a central nucleus. The oolite systern is largely developed in Englan.d, France, West~halia, and. Northern Italy; it appears In Northern Ind~a and Afnca, and patches of it exist in Scotland, and 1!1 the val~ of the Mi issippi. It may of course be yet discovered 1n many other parts of the world.. . . The series, as shown In the neighborhood of Bath, IS (beginning with the lowest) as ~ollows :-1. I..ias, a set or strata variou ly composed of limestone, clay, marl, and shale,' clay being predominant; 2. Lo~er oolitic formation, includino·, be ides the great ool1te bed of central Eno-land, fuller ' earth beds, forest marble, and corn brash; 3. rVIiddle oolitic formation, compo ed of two sub-groups, the Oxford clay and coral ra~, the latter being a mere ' layer of th work of the coral polype; ~· U pp~r oolitic formation includinu· ·what are called K1mmendge clay anu Portl~nd oolite. In Yorlchire, there is an additional group above th lia , and in Sutherland hire, there is another group above that again. In the wealds (moorlands) of Kent Rnd ~u: ex, there i , in like manner, above the fourth of the Bath seri , another additional group, .to which the name of the 'fVcalden ha been given, from 1ta situation, and which, cotnpo 'Cd of sandstones and cla)'s, is subdivided into Purbeck beds, Hastings sand and Weald clay. COMMEN :-'EMENT OF MAMMALIA. 57 "fhet·e are no particular appearances of disturbance be~ een the close of the new red sandstone and the beginni~ w of the oolite system, a~ far as has been observed in England. Yet there is a great change in the materials of the rocks of the two formations, showing that while the bottoms of the seas of the one period had been c.hiefly arenaceous, those of the other were chiefly clayey and li~y. And there is an equal difference between ~he two perwds in respect of both botany and zo0logy. While the ne~ red sandstone shows comparatively ~canty traces of organ.Ic creation those in the oolite are extremely abundant, particularly in 'the department of animals, and more particularly still of sea mollusca which it has been observed, are always the more conspicu~us in proportion to the predomin.ance of calcareous rocks. It is also remarkable that the animals of the oolitic system are entirely different in species from those oftlv~ preceding age, and that ~hese.spectes cease b~fore the next. In this system we likewise find that uniformity over great space which has been remarked of i!1e Faunas of earlier formations. ''In the equivalent deposits in the Himmalaya Mountains, at Fernando .Po, in the re(l'ion north of thP. Cape of Good Hope, and 1n the Run of° Cutch, and other parts of Hindostan, fos~ils have been discovered, which, as far as English naturalists who have seen them can determine are undistinguishable from cer· tain oolite and lias fossils of Europe."* . The dry land of this age presented cycadere., "a bea~hful class of plants between the palms and conifers, havtng a tall, straight trunk, terminating in a mag.nificent crown of foliage. ''t There were three ferns, ?ut In sma~l~r proportion than in fonner ages; also equtsetacere, lllta, and conifers. The vegetation was generallJ anal~gous to that of the Cape of Good Hope and A ustralla, .wh1ch se~ms to argue a climate (we must remembet· a universal climate) between the tropical and temperate. It was, howeve_r, sufficiently luxuriant in some i~stances t? produc~ thin seams of coal, for such are found In the oohte formatiOn of both Yorkshire and Sutherland. The sea, as for ages before, contained algre, of which, however, only a few species have been preserved to our day. The lower classes of the inhabitants of the ocean were unprecedently abundant. The polypiaria were in such abundance as to form wl·ole • Murchison's Silurian System, p 583. t Buckland |