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Show 230 .EXPLANATIONS. nP- regard~ the histot·y of the class a~ so far from com_r~ete, that the .1umber of species successLvely entombed 1n the crust of the globe mio-ht be estimated at thirty thousand, without any ch'l.nce of approaching the truth!* If such be the case, we may surely expect to hear of other fis~es prior to or contemporary with the cestraceon, showt ng that humble as that animal was, it is not to be regarded as the initial of its class.t But even although simpler fishes be not fouad in lower or contemporary strata, this may only 'be owing, like the nor:t-discovery of veget~tion in the early rocks, to the unsu1tablenes.s of these fishes for being preserved. Supposing the infer~or tr~bes, petrotnyzonidre (lampreys) to have been then 111 extstence, we should have no trace of them preserved, because of their osteologic structure being slight, and their wanting those teeth and spines which form, after all, the chief memorials of the higher families of their own order. One ·word more as to these fishes. The critic says (p. 33,) it is shown to demonstration in the Poissons Fossiles of Agassiz, that " the sauroids, in their general osseous structure, and in the development of their nobler organs, run close upon the class of reptiles." There is no doubt that the sauroid fishes partake of reptilian characters, though, perhaps, in a more extt-rnal and less important way than such writers as the Edinburgh reviewer suppose; but, be it remembered, the sauroids are not the first fishes. There is not one of them in the Silurian formation, where placoideans appear to begin. Yet I do not, for this reason, suppose that the sauroids arose from pla.· coideans. More probably, they are part of a distinct line of development, which had inferior forms in its first stages, also of too slight a structure to be preserved. Following this reviewer into his discussion of the Carboniferous System, vve find him commencing with a taunt, that there are now traces of land vegetation in • Review of Professor Pictet's Traite Elementaire de Palreonto logie, translated in Jameson's Journal from the Bibliotheque Uni· verselle de Geneve, No. 112, 1815. t Such shirts are of frequent occurrence in geology. Insects, !ormerly found first in the oolitic formation, are now taken ba~k tto the carboniferous. Birds are now inferred from fvot-tracks m thH New Red Sandstone, their first place formerly being in the oolite. We have mammifers in the oolite, which, a few years ago, were believe<l not to occur before the tertiary. None of tbese •hifts, however, in the least interfere with the gener fact of tho advance from the lower to the higher classes of animals. I'OSSILS OF OI.D RED SANDSTON.E 231 earlier formations. This is, in reality, a poiut of no importar: tce for th.e development theory. The question Is, With .what lnnd of plants did land veo-etation beo-in 'l !'he anxiety of the reviewer to force a verdict in his l'avo; ls here strongly shown. "What " he says " th fi · t f · t f , , , are ese . r s r~1 s o nature s vegetable germs ? Are they rude 111-fashwned forms ? Far otherwise. We find amon ' them pa~ms and tree-ferns, &c." In this passao-e whic~ · substaJ?-tially co.nveys th~ same .information as ~y book, there I:.s an evident ~esign of Inducing the belief that t~e. first lan.cl vegetation was of a high character. The rigid truth Is, t~at though this was a " grand" in the sense .of a lu.xunant vegetation, it was composed, as far as posth ve ~vidence goes, almost wholly of plants which s~and low In the scale of organization. The ascertained dicot~ledons (plants having double-lobed seeds and an extcnor growth) are extremely rare. On this point, 1 cann~t ~o ?etter than quote the lat>Orious young Profes .. sor of King. s Coll~ge-" The plants which have hitherto b~en descnbed [In the carboniferous formation] belong either to the acotyledonous class, as the ferns, or to the n:onocotyledons, and, on the whole, they constitute the nmples.t {orms of vegetation; but there have also been d~et Wit among coal plants unquestionable evidences of ICotyledonous structure, and a genus has been formed under the na!fie of Pinites, to include a number of specimens of fossil wood, &c."* To the undoubted evidence of Mr · Ansted may be added that of his more eminent contemporary,. Mr. Lyell, whose sense of the botanical character of th1s age is ~uch .that he emphatically calls it the Age of ?erns.t It Is evident, then, taking the landscap~ of t~Is era as the first, that it is of a nature to harmomze with the developm~nt theory, for its chief forms are humble, a~d only a few ar~ of higher grade most of these, too, being of. an intcrntediate character 'between the low and the high.. I am rmninded, however, in other. quarters of certatn experiments of Dr. Lindley showi~g that ~he plants c~iefly found in the coal ar~ of the lnn~s . W:hJ.Ch best resist decomposition in water· whence .It Is Inferred .that many trees of a high class may nave ex1sted at that time, but perished in the sea wh '1 lltea}(P.r vegetation survived. This evidence w~uld ~: "' Ans~ed's Geology, 1844. t Travels m North Amexica, ii., 52 |
