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Show 146 THEORY OF any memorials,) the vegetation consisted almost e_ntirely of cryptogamic plants, while the animals which co-existed were almost entirely confined to zoophytes, tcstacea, and a few fish. Plants of a less simple structure succeeded in the next epoch, when oviparous reptiles bcga~ als? to abound. Lastly, the terrestrial flora became most diversified and most perfect when the highest orders of animals, the mammifera and birds, were called into existence. Now, in the first place, we may observe, that many naturalists have been guilty of no small inconsistency in endeavouring to connect the phenomena of the earliest vegetation with a nascent condition of organic life, and at the same time to deduce, from the numerical predominance of certain types of form, the greater heat of the ancient climate. 'l~he arguments in favour of the latter conclusion are without any force, unless we can assume that the rules followed by the Author of Nature in the creation and distribution of organic beings were the same formerly as now ; and that as certain families of animals and plants are now most abundant, or exclusively confined to regions where there is a certain temperature, a certain degree of humidity, intensity of light, and other conditions, so also the same phenomena were exhibited at every former era. If this postulate be denied, and the prevalence of particular families be declared to depend on a certain order of precedence in the introduction of different classes into the earth, and if it be maintained that the standard of organization was raised successively, we must then ascribe the numerical preponderance in the earlier ages of plants of simpler structure, not to the heat, but to those different laws which regulate organic life in newly created worlds. If, according to the laws of progressive development, cryptogamic plants always flourish for ages before the dicotyledonous order can be established, then is the small proportion of the latter fully explained ; for in this case, whatever may have been the mildness or severity of the climate, they could not make their appearance. Before we can infer an elevated temperature in high latitudes, from the presence of arborescent Ferns, Lycopo· , diacere, and other allied families, we must be permitted to assume, that at all times, past and future, a heated and moist atmosphere pervading the northern hemisphere has a tendency to produce in the vegetation a predominance of analogous SUCCESSIVE DEVELOPMENT. 147 types of form. we grant . d nexion between an extr ,, dl~ eed, that there may be a con-aor mary p f · f donous plants, and a youthful c . ~o uswn o monocotyle-dogma of certain cosmogonist b ondttwn of the world, if the projectiles, are always red hot ~true, that planets, like certain this arbitrary hypothesis w wden they are £rst cast; but to e nee not agai Between two and th ree h un d red s · n rfe vert. enumerated as belonging t th pecies o plants are now very few exceptions, not o~e o~ ~~::niferou~ era, and, with But these exceptions are as fatal to th are ~Icotyledonous *· development as if there w h e doctrme of successive ere a t ousand Ith h not by any means invalidate the . ' a. oug they do heat of the ancient climate fo th ~oncluswn m regard to the relations of the different I' r a depends on the numerical . c asses. The ammal remains in the most . . sedimentary rocks (from th ancient senes of European consist chiefly of corals a:d g::?wacke to the coal.inclusive ), generally be formed of th tac~a. Some estimate may · e comparative ext t f · tton concerning the fiossil remam. s of a t•e n 1 o our mforma-ence to the number of . f par Icu ar era, . by refer-ti~ ular group of strata. sp~c~:e :f shells obtained. from a pardiscovered, unless the more abu d the r~rest species cannot be again and again; and if the ~ ant kmds hav~ been found considerable, it proves not onl;ar~et~ ~~tught to hght be very a good state of re t. g ea I Igence of research, but formation In tPh selrdv a Ion ko f the orgam·c contents of that ~ave · e o er roc s man f operated, of which the infl' y causes o destruction Siderable b the i uence has been rendered conacted. J.ch .mml ense lapse of ages during which they have movements thea maccati prefs suhre ' .d era ngement b y subterranean acidulous ~aters ano: :th:r emical.affinity, the percolation of greater or less d agencies, have obliterated, in a Sometimes only e~ee, all trace~ of o~g.anization in fossil bodies. o scure or unmtelligtble impressions are left, * Fragments of dicotyledonous wood hi h h . two different species of tree h b w c ave evidently belonged to at least b! Dr. Fleming, of Flisk, a~d :~: s:en obtained from the coal-field of Fife, dicotyledonous stem h. h h me gentleman has shewn me a large memoir by Dr. Flemi: I~n the pr~cured from the graywacke of Cork. See a Edin.) I am informal also be neighbourhood of Cork. (Trans. of Wern. Soc. ~eld of Northumberland t~ Dr. B~ckland, that he has received from the coalIn the Oxford Museum. ano er speCIJDen of dicotyledonous wood, which is now L2 |