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Show 240 EXPLANATIONS. ent view was first hinted at· and in the fourth it wa.. sketched, though with liability to.cor~·ection; thu.s .aJ?tici pating by some months the pubhcatwn of the cnhcis~ to which I am advertinrr. I need hardly remark, that In all criti,~ism, the actual ~ubject c1:iticiscd must be ~rought forward for comment and nothing else; otherwise the comrnentaries become' of no imaginable use but to obscure h·ue judgment. Now the Edinburgh reviewer has presented h.. .i. s subject, in this insta1~ce, in .lineamen~s ~ntirely of his own imagining? and d1rectly In .contradiction to those which belong to It. He had no title to assume any plan of dc~elopment and to repres.ent hi.s victory over that as a tnurnph over the hypothesis of Ius author. In such conduct he has thoroughly vitiated the whole fabric of his criticism, and left it, in reality, no pretension to remain for a moment in court. My immediate object, .however, is not to take s~ch exceptions ~ga~nst him, but to show how the ascertained facts of a limited portion of the field of nature may be reconciled with that conception to which a view of what appears over the ·whole field may lead an honest inquirer. If the hypothesis of a plurality of gel!etic lines be admitted, we are not of course to ask which order of reptiles, or of any other class, first existed (such beihg the language of the old classification;) but, having first settled the whole affinities of the animal kingdom on the new plan, we are to inquire if th.e geological present~ent vt the families was accordant with the scheme~ allow~ng for the negative nature of nntch of the geologtca.l.evidence of this kind. N'JvJ, in the first place, the affinities of the animal kingdon1 are only in part made out; in the second, geological evidence is only partial. We are clea~,l~, therefore, not to expect in nature's museum a full exlubition of any one entire stirps, as it may be supposed to have passed through its successive ~tages up t.o our ti~1e All that we can expect is a successiOn of fossils markmg out portions of what we may suppose likely yet to be established as lines of animal descent. Blanks, and large ones too, must be allowed for; possible errors as to the animal pedigrees must be co.ntempla~ed. B~t if ~e have any ground for generalizing In a partteular duectwn, as I think there is in this case, we may be held as called upon not to conclude hastily and rashly on the unfavorable side, but to look and consider patiently, and to suspend EARLY REPTILIAN FOI1SIL8 241 rttdtment wherever the adverse evidence may appear to Oe of a nature likely to be reversed. Let us now see how all this applies to the conduct of the Edinburgh reviewer, with regard to the early reptilian fossils. The formations where these occur have only been examined in such a degree, that they are almost every year giving forth new responses: for example, the existence of birds at this era was not dreamt of ten years ago; the existence of tortoises in the time of the New Red Sandstone was equally unknown only two or three years earlier. It is a still less time since the labyrinthidonts of the Keuper of Germany were discovered; and we have just seen that the unqualified affirmations of the Edinburgh reviewer, as to the oldest reptiles, were overturned by intelligence from America, before his sheets had seen the light. When these things are considered, we must see t~e objections _of the reviewer to be extremely rash. It m1gbt be allowed that the earliest known lacertilia are not of strictly marine forms or allied to fish; it might equai!J be admitted of the first batrachians, that "their near affinities are not with fishes," as this writer takes upon him to say. Yet we should still see the absurdity of affirming that either these batrachia or lacertilia were the first created of their respective orders, seeing that their relics were so few and the discovery of these so accidental, that we might look for new and superseding facts every day .11 But as the case actually stands, is this line of defence more 'than hypothetically necessary? I doubt it very much. The lacertilia of the magnesian limestone, and these labyrinthidonts of the Trias (perhaps also of the carboniferous formation;) are they so far removed from fish characters as the reviewer would make them? Let any naturalist who has ever studied the transmutation of the individual batrachian, passing in a few weeks from the branchiated fish to the lunged and limbed frog or newt, its circulatory and alimentary system entirely J • It is necessary to gu~rd a&"ainst a supp~sition that I und~rvalue such isolated relics, as Jnferrmg the pos1hve fact of the existence of particular orders of animals at particular times. For this purpose, the smallest ~r~gment betraying the charac~er of the organization is often sufficient. What 1s r~ally meant 1s, that, ~hen we find a few outlying relics belonging to a class which does not appettr in any force till afterwa~ds, we ?a~not. be sure that. we ha7e acquired the means of formmg a d1stmct 1dea of the tune of t1&6 "rigin of ihat cla.ss or the order.s with which the class started., aa further discovenes on these oomts may be looked for. 19 |