OCR Text |
Show 242 EXPLANATION! chanO'ed and then say if the labyriuthidon nay not be the very first step from some ichthyic. form. What though the proportions of the head remind M~. Owen of tho sauria, and remove the animal, as he thmks, .above the present batrachian type! Against any s?ch. tnferenc~s we have the positive fact, in the organization of this batrachian, of a biconcave form of the vertebrce, the form pecuiiar to fishes,-arguing. ?Y Mr. qwen's own ack.nowl· edcrment aquatic if not manne hab1ts,-also a decidedly pis~c ine c' haracter in the arrangement a!l d even m~.c ~o-scopic structure of the teeth, together with that posihon of the breathing apertures near the end of the sn?ut which v1e see in crocodiles, for the purpose of allowing them to drag their prey under wa.t~r without cea.s-ing to respire. With regard to the lacertilia. '\Ve have this same fish-like biconcave form of the vertebrce, and the same fish-like arrangement of the teeth, equally.arg~ing that alliance to the lower vertebrate class which It Is the pleasure of this hardy critic to deny,-the bico.ncave structure of the reptiles, sho,ving, as Mr. Owen ht~self owns that these animals, ·which the Edinburgh reviewer deem~ so utterly separated from fish, had probably "a more aquatic, ·if not marine theatre of life,"* than was assigned to .their su~cessors. In subsequent and present reptiles this form IS superseded by the ball and s?cket, or conc~vo-convex form; but it is remarkable that, Hl the embt·yo state, the frog and crocodile (if n?t o!hers) exhibit the double hollow form still, resembling 1n this l'C· suect the mature animal of the secondary rocl~s: Sue~ is the actual character of reptiles which our en tic would set up a8 high: he has, after this, only to speak of t.he annelid as above the butterfly, or the proteus as supenor to the land salamander, to establish hi~ chara~ter as a naturalist. Need I say that these Perm1an .rephle~ a~e, in reality, by these facts degraded to a place In proximtty with fishes ? 0 much for the batrachia and lacertilia. When .we cmne to the great saurian line in the lVIuscpelkalk, Lias, Oolite, and Wealden, we have a case which can~ot be jisputed, for here t~1e .marine c.haracter of the earliest of !.he series. and the1r Intermedtateness betweP.n fish and n·ue crocodiles, are admitted by all. The first remove + On the Reptilian Fossils of South Africa Geological Trani actions, .r.·eb., 1845. EARLY REPTIJ~IA.N FOSSILS. 243 iom the fish is the ichthyosaur, its name declaring the convention of class characters for which it is remarkable. Wjth pi~cine body and tail, and fins advanced into a paddle form, it has a true crocodilian head. In the pliosaur, which is later in appearing, we have a stage of advance to the true sauria, which come forward in the oolite, in the forms ofteleosaurus, steneosaurus, &c. Afterwards, chiefly in the Wealden, we have the dinosauria, which betray an approach to the mammalian type in the pachydermatous order. Another oolite saurian, the cetiosaur, exhibits in the form of the_ vertebrce a verging towards the cetaceous rnammalia. Here there is the most perfect and even striking harmony with the theory of a progressive development. Below these formations, fish; then, low in these formations, fish saurians; above them, true and complete saurians; finally, higher still, saurians advancing to a more elevated grade of animality; and where do these more elevated types occur? In the next formation passing over one which hardly represents any but deep-sea life. Nay, cetaceous relics have been found before we leave the strata so remarkable for the saurians. Thus it appears that the whole of this chapter of palreontology, when read by a light from nature, and not from man's capricious humor, so far from being opposed to the natural genesis of anirnals, gives it support. Men, however, and of lively parts too, might go on for an age misreading such palpable facts, if they be determined against putting then1 into the collocation ·in which a sense can be made of them, just as we might puzzle forever over a Latin or Greek sentence, if obstinately resolved against making English out of it excnpt in its origiual construction. J After presenting the case of the reptilian fossils of the secondary formation in this way, I feel it hardly necessary to track the Edinburgh reviewer through all his particular objections. They are a mass of confusion, resulting from erroneous assumptions on his own part respecting the development theory, as that the orders of animals are all to be affiliated to each other, and every parental form held as extinguished by the fact of transmutation (the latter being a pP.culiarly gratuitous supposition-see p. 50 of the Review:) together with equally rash and unjustified conclusion~ regarding the earliest forms of the reptilian orders, all mixed up in a way that promised to tell mos~ effectually in favor of his own opinion, and with |