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ner all the solid parts of many fishes have disappeared, although the impressions oftheir external coverings or scales remain as distinct as if they had been drawn fromlife. The frequent association, also, of gypsum in large quantities with the salt-bedsof this formation may also suggest other causes;—its occurrence is not improbably ofsecondary origin. In England, the Muschelkalk is only very faintly represented, ifit exist at all, but on the Continent it forms the central member of the formation.By the occurrence of the ammonitic type of Cephalopoda it approximates to the nextperiod, and it may well be doubted whether a formation in which arenaceous beds sostrongly predominated should be kept distinct, as such a character bespeaks a partialorigin, and indicates a portion rather than a whole. It is well known that the foot-steps of a remarkable animal long noticed on the beds of the New' Red Sandstonehave been traced to the Labyrinthodon, a reptile between the Saurian and Batrachiantypes, whose remains have been found in the Muschelkalk ; but the recent discoveryof similar footsteps in Pennsylvania , in strata considered of the age of the Old RedSandstone, will carry the origin of reptile life up to that remote epoch, should thedetermination of the age of the deposit prove correct. Mr. Lea has called the animalof which these footsteps are as yet the only records, Sauropus primsevus. The Che-lonians or Tortoises appear for the first time in the list, affording another analogywith the Oolitic period. The flora, according to M. Adolphe Brongniart, affords amore certain element of comparison, as it no longer, like the Permian, exhibits stronganalogies with the Carboniferous , but differs from it in a marked manner.
That distinguished botanist points out that two causes of difference must beadmitted in fossil flora;, the one due to change of epoch, the other to difference ofgeographical position,—just as in the present time there are local variations, aforest of Pinus sylvestris growing in Germany , one of Abies taxifolia in the Vosges,of Picea excelsa in the Jura , and of Pinus pinaster in the Landes. This is veryevident in the flora of the Permian system ; but though the local florae of the epochwere specifically varied, they possess a common relation to the flora of the Coal formations, of which they appear to be an extract. Turning, however, thispoint, a great botanic change takes place, and the Trias and Oolitic periods arelinked together by the prevalence of plants belonging to another great division of thevegetable kingdom, the Gynmosperms. This difference in the flora; of successiveepochs, and the equally striking differences between the fossil and recent flora, shouldbe sufficient to satisfy even those who still hesitate to receive the evidence whichGeology affords of extinct worlds. Brongniart, for example, states that the Coal formations of Europe have as yet produced only 500 species, whilst the flora ofEurope includes about 11,000; but if the Ferns of the two periods be compared,the disparity is in the other direction, as the Coal formation of Europe has alreadyproduced 250 species, and the whole of Europe now only produces 50. When,therefore, this difference in arrangement is combined with the variation of form, alsoso manifest, is it possible that even the most sceptical on geological truths can per-severe in attempting to consider all these extinct organisms as only portions of theexisting creation ? In Plate X. of ‘ Geology’ some of the most remarkable fossils ofthe Trias are figured. As this is, as it were, the turning-point from the more ancientorganic condition of the earth’s surface, it may be well to abstract briefly some of theconclusions of Mr. W. King in his recent Monograph of Permian Fossils. The genusProductus, so characteristic of the fauna of the Carboniferous epoch, and well exhi-bited in the Permian , appears also in the marls of St. Cassian,— so that some doubtmay be felt as to the age of the latter. In the Permian system, remains of the tetra-branchiate division of Cephalopoda , or of the Cephalopoda with external shells andinternal siphons, have alone, as yet, been found; whereas Rliyncolithes, or the man-
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