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Show 36 SEA PL-\N'l'S, CORALS, ECT. mean organization and-ferocious habits, of which the sl:.atk and sturgeon are living specimens. " Some were furnished with long palates, and squat, firmly-based teeth, well adapted for crushing the strong cased zoophytes and shells of the period, fragments of which occur in the fmcal relnains ; some with teeth that, like the fossil sharks of the latter formations, resemble lines of miniature pyramids, larger and smaller alternating; ~orne with teeth sharp, thin, and so deeply serrated, that every individual tooth resembles a row of poniards set up against the walls of an armory ; and these last says Agassiz, furnished with weapons so murderous, must have been the pirates of the period. Some had their fins guarded with long spines, hooked like the beak of an eagle; some with spines of straiter and more slender form, and ribbed and furrowed longitudinally like columns; some were shielded by an armor of bony points, and some thickly covered with glistening scales."* The traces of fuci in this system are all but &ufficient to allow of a distinction of genera. In some parts o1 North America, extensive though thii' ~eds of them have b~en found. A distinguished Fr--acn geologist, M,. Brogniart, has sho\\~n that all existing marine plants are classifiable with regard to the zones of climate; some being fitted to the torrid zone, some for the temperate, some for the frigid. And he establishes that the fuci of these early rocks speak of a torrid climate, although they may be found in what are now temperate regions; he also states that those of the higher rocks betoken, as we ascend, a gradually diminishing temperature. \Ve thus early begin to find proofs of the general uniformity of organic life over the surface of the earth, at· the time when each particular system of rocks was formed. Species identical with the remains in the Wenlock limestone occur in the corresponding class of rocl<;s in th~ Eifel, and partially in the Harz, Norway, Russia, and Bntta!lJ. The situations of the remains in Russia are fifteen hundred tniles from the Wenlock beds ; but at the distance of between six and seven thousand from thosen~ mely, in the vale of Mississippi, the same species are discovered. Uniformity in animal life over large geographical areas, argues uniformity in the conditions of. anirnallife; and hence arise some curious inferences. Spe· ... ,.ies, in the same low class of animals are now much more ,. Miller's" New Walks in an Old Field." ERA OF TllE OLD n tD f!.A.NDSTONE. 37 tin1ited; for instance, the Red Sea gives different polypt• aria, zoophytes, and she 11-fish, from the Mediterranean. It is the opinion of 1\1. Brogniart, that the uniformity which existed in the primeval times can only be attributed to the temperature arising from the internal heat, which had yet as he supposes, been sufficiently great to overpower the ordinary meteorological influences, and spread a tropical clime all over the globe. ERA OF THE OLD RED SANDSTONEFISHES ABUND.ANT. WE advance to a new chapter in this marvellous history- the era of the Old Red Sandstone Syste·m,. This term has been recently applied to a series of strata of enormous thickness in the whole mass, largely developed in Herefordshire, Shropshire, W orcestershire, and South Wales; also in the counties of Fife, Forfar, Moray, Cromarty~. and Caithness; and in Russia and North America, if not in many other parts of the world. The particular strata forming the system are somewhat different in different countries ; but there is a general character to the extent of these being a mixt~re of flagstones, marly rocks, and sandstones, usually of a laminous structure, with conglo· merates. There is also a schist showing the presence of bitumen; a remarkable new ingredient, since it is a vegetable production. In the conglomerates, of great extent and thickness, which form, in at least one district the basis or leading feature of the system, inclosing water .. worn fragments of quartz and other rocks, we have evi .. deJ?-ce of the seas of that period having been subjected to a vwlent and long-continued agitation, probably from volcanic causes. The upper members of the series bear the appearance of having been deposited in com:raratively tranquil seas. The English specimens of th1s system show a remarkable freedom from those disturbances which result in the interjection of trap ; and they are thus defective in mineral ores. In some parts of England the old red sandstone system has been stated at 10,000 feet in thickness. In this era, the forms of life which existed in the Silurian ~re continued: we have the same orders of marine |