assembled here-coal and iron. We deal more in facts; but if our members would only look around them, they would soon perceive that nearly all their necessaries and luxuries, whether of food or clothing, or of the adornment of their mansions, are furnished by animal and vegetable products. This, however, depends upon ourselves, and if we will study these wonderful productions with minds impressed with the power and goodness of God in placing them around us, we shall find the investigation of them no weary work, but one full of interest and information. By these remarks I do not wish to claim for the British Association any undeserved influence; but it is now universally acknowledged that the example it has shown, and the various links it has joined between the different departments and the people cultivating them, have had a very decided influence on the promotion of science. At all the meetings of this Association which I have attended I have observed a great impulse given both in the preparation for the meetings and after their conclusion, and if you will give it your attention, you will find that after we have left you, various matters will appear in other lights than you formerly viewed them. Various subjects will be suggested to you, and many of you will try to study and master this or that subject as your inclination leads, and my wish is that you may persevere and be successful. On the Orders of Fossil and Recent Reptilia and their Distribution in Time. By Professor OWEN.-Professor Owen began by remarking that, with the exception of geology, no collateral science had profited so largely from the study of organic remains as zoology. The catalogues of animal species had received immense accessions from the determination of the nature and affinities of those which had become extinct, and much deeper and clearer insight had been gained into the natural arrangement and subdivision of the classes of animals since palæontology had expanded our survey of them. Of this the class Reptilia, or cold-blooded air-breathing Vertebrates, afforded a striking example. In the latest edition of the "Règne Animal," of Cuvier, 1829, as in the "Elémens de Zoologie" of M. Edwards, 1834-37, and the still more recent monograph on American Testudinata by Agassiz, 4to, 1857, the quadruple division of the class, proposed by Brongniart in 1802, was adhered to,—viz., Chelonia (tortoises, turtles), Sauria (crocodiles, lizards), Ophidia (serpents), Batrachia (frogs, newts); only the last group is made a distinct class by the distinguished Professor of the United States :-" After this separation of the Batrachians from the true Reptiles, we have only three orders left in the class of Reptiles proper,-the Ophidians, the Saurians, and the Chelonians" (1. c. p. 239). In Professor Owen's Reports on British Fossil Reptiles to the British Association in 1839 and 1841, it was proposed to divide the class into eight orders, viz.,-Enaliosauria, Crocodilia, Dinosauria, Lacertilia, Pterosauria, Chelonia, Ophidia and Batrachia, which were severally characterised. Subsequent researches had brought to light additional forms and structural modifications of cold-blooded air-breathing animals now extinct, which had suggested corresponding modifications of their distribution into ordinal groups. Another result of such deeper insight into the forms that have passed away has been the clearer recognition of the artificiality of the boundary between the classes Pisces and Reptilia of modern zoological systems. The conformity of pattern in the arrangement of the bones of the outwardly well-ossified skull in certain fishes with well-developed lung-like air-bladders (Polypterus, Lepidosteus, Sturio), and in the extinct reptiles, Archegosaurus and Labyrinthodon; the persistence of the notochord (Chorda dorsalis) in Archegosarus as in Sturio; the persistence of the notochord and branchial arches in Archegosorus and Lepidosiren; the absence of occipital condyle or condyles in Archegosarus as in Lepidosiren; the presence of teeth with the laby rinthic interblending of dental tissues in Dendrodus, Lepidosteus and Archegosarus, as in Labyrinthodon; the large median and lateral throatplates in Archegosarus as in Megalichthys, and in the modern fishes Arapaima and Lepidosteus;-all these characters, as the author had urged in his Lectures at the Government School of Mines (March 1858), pointed to one great natural group, remarkable for the extensive gradations of development, linking and blending together fishes and reptiles within the limits of such group. The salamandroid (or so-called "sauroid") Ganoids-Lepidosteus and Polypterus-are the most ichthyoid, the Laby-rinthodonts the most sauroid, of the great group; the Lepidosiren and Archegosaurus are intermediate gradations, one having more piscine, the other more of the reptilian character. Archegosaurus conducts the march of development from the fish proper to the labyrinthodont type; Lepidosiren conducts it to the perennibranchiate, or modern batrachian, type. Both forms expose the artificiality of the ordinary class-distinction between Pisces and Reptilia, and illustrate the naturality of the cold-blooded Vertebrates, or "Hæmatocrya" da, blood, xevos, frost: (the correlative group is the "hæmatotherma"). Reptiles are defined as "cold-blooded, airbreathing Vertebrates"; but the Siren and Proteus chiefly breathe by gills, as did most probably the Archegosarus. The modern naked Batrachia annually mature, at once, a large number of small ova. The embryo is developed with but a small allantoid appendage, and is hatched with external gills. These are retained throughout life by a few species; the rest undergo a more or less degree of metamorphosis. Other existing reptiles have comparatively few and large eggs; and the embryo is enclosed in a free amnios, and is more or less enveloped by a large allantois. It undergoes no marked transformation after being hatched. On this difference the Batrachia have been by some naturalists separated as a distinct class from the Reptilia. But the number of ova simultaneously developed in the viviparous land salamanders is much less than in the siren, and not more than in the turtle; and, save in respect of the external gills, which disappear before or soon after birth, the salamander does not undergo a more marked transformation, after being hatched, than does the turtle or crocodile.* It depends, therefore, upon the value assigned to the different proportions of the allantois in the embryo of the salamander and lizard whether they be pronounced to belong or not to distinct classes of animals. This embryonic, or developmental character, is unascertainable in the extinct Archegosaurus and Labyrinthodon. The affinity of Labyrinthodon to Ichthyosaurus, and those structures which have led the ablest German palæontologists to pronounce the Labyrinthodonts to be true Saurians, under the names of Mastodonsaurus, Trematosaurus, Capitosaurus, &c., may well support the conjecture that modifications more "reptilian" than those in Salamandra may have attended the development of their young. Characters derived from the nature of the cutaneous coverings equally fail to determine the class characters of Batrachia as contra-distinguished from Reptilia. It is true that all existing Batrachia have a scaleless skin, or very minute scales (Cæcilia), but not all existing reptiles have horny scales. The crocodiles and certain lizards show a development of dermal bones similar to that in certain placoid and ganoid fishes. This development is greater, and the resemblance is closer, in those ancient forms of Reptilia which exhibit in their endo-skeleton_unmistakeable signs of their affinity to ganoid fishes and Batrachia. In a survey, therefore, of the present known forms of cold-blooded, airbreathing Vertebrates, recent and fossil, Professor Owen could not define * The Cæcilia may probably depart still further from the type-batrachian mode of development, and approach more to the type-reptilian mode. any real and adequate boundary for dividing them primarily into two distinct classes of Batrachians and Reptiles. As little was he able to point out a character dividing the air-breathing from the water-breathing Hæmatocrya-the reptiles from the fishes. In the present communication the author drew an arbitrary line between Lepidosiren and Archegosaurus, and proposed to begin his review of the ordinal groups of Reptilia, or airbreathing Hæmatocrya, with that of which the Archegosaurus was the type. Order I. GANOCEPHALA.-For this group or order he proposed the name of Ganocephala (yavos, lustre, xean, head), in reference to the sculptured and externally polished or ganoid bony plates with which the entire head was defended. These plates include the "postorbital” and “ supertemporal" ones, which roof over the temporal fossæ. No occipital condyles. The teeth have converging inflected folds of cement at their basal half The notochord is persistent; the vertebral arches and peripheral elements are ossified; the pleurapophyses are short and straight; pectoral and pelvic limbs, which are natatory and very small; large median and lateral" throat-plates;" scales small, carinate, sub-ganoid; traces of branchial arches. The above combination of characters gives the value of an ordinal group in the cold-blooded Vertebrata. The extinct animals which manifest it were first indicated by certain fossils discovered in the sphærosideritic clay-slate forming the upper member of the Bavarian coal-measures, and also in splitting spheroidal concretions from the coalfield of Saarsbruck near Treves; these fossils were originally referred to the class of fishes (Pygopterus lucius, Agassiz). But a specimen from the "Brandschiefer" of Munster-Appel presented characters which were recognised by Dr Gergens to be those of a Salamandroid reptile.* Dr Gergens placed his supposed "Salamander" in the hands of M. Hermann von Meyer for description; who communicated the result of his examination in a later number of the under-cited journal.† In this notice the author states that the Salamander affinities of the fosil in question, for which he proposes the name of Apaeton pedestris, "are by no means demonstrated."‡ "Its head might be that of a fish, as well as of a lizard, or of a batrachian." "There is no trace of bones of limbs." M. von Meyer concludes by stating that, "in order to test the hypothesis of the Apateon being a fossil fish, he has sent to Agassiz a drawing, with a description of it." Three years latter, better preserved and more instructive specimens of the problematical fossil were obtained by Professor Von Dechen from the Bavarian coal-fields, and were submitted to the examination of Professor Goldfuss, of Bonn; he published a quarto memoir on them, with good figures, referring them to a Saurian genus, which he calls Archegosaurus, or "primeval lizard,"-deeming it to be a transitional type between the fish-like Batrachia and the lizards and crocodiles. The estimable author, on the occasion of publishing the above memoir, transmited to Professor Owen excellent casts of the originals therein described and figured. These casts were presented by the Professor to the Museum of the Royal * "Mainz, Oktober, 1843.-In dem Brandschiefer von Münster-Appel. in Rhein-Baiern, habe ich in vorigen Jahre einen Salamander aufgefunden. Gehört dieser Schiefer der Kohlen-formation? in diesene falbe wäre der Rund auch in anderen Hinsicht interessant." Leonhard und Bronn, Neues Jahrbuch für Mineralogie &c., 1844, p. 49. † Ibid. 1844, p. 336. "Ob das-Apateon pedestris-ein Salamander-artiges Geschöpf war, its keineswegs ausgemacht." § "Archegosaurus: Fossile Saurier aus dem Steinkohllengebirge die den Uebergang des Ichthyoden zu den Lacerten und Krokodilen bilden." p. 3. Beitrage zur vorweltlichen Fauna des Steinkohlengebirges." 4to. 1847. College of Surgeons, London, and were described by him in his "Catalogue of the Fossil Reptiles," in that Museum (4to. 1854). The conclusions which Professor Owen formed thereupon as to the position and affinities of the Archegosaurus in the reptilian class, are published in that Catalogue, and were communicated to and discussed at the Geological Society of London (see the "Quarterly Journal of the Geological Society," vol. iv. 1848). One of the specimens appeared to present evidence of persistent branchial arches. The osseous structure of the skull, especially of the orbits, through the completed zygomatic arches, indicated an affinity to the Labyrinthodonts; but the vertebræ and numerous very short ribs, with the indications of stunted swimming limbs, impressed the writer with the conviction of the near alliance of the Archegosaurus with the Proteus and other perennibranchiate reptiles. This conclusion of the affinity of Archegosaurus to existing types of the reptilian class is confirmed by the subsequently discovered specimens described and figured by M. von Meyer, in his " Palæontographica" (Bd. vi., 2te Hef. 1857), more especially by his discovery of the embryonal condition of the vertebral column-i.e., of the persistence of the notochord, and the restriction of ossification to the arches and peripheral vertebral elements. In this structure the old carboniferous reptile resembled the existing Lepidosiren, and afforded further ground for regarding that remarkable existing animal as one which obliterates the line of demarcation between the fishes and the reptiles. Coincident with this non-ossified state of the basis of the vertebrate bodies of the trunk is the absence of the ossified occipital condyles, which condyles characterise the skull in better developed Batrachia. The fore-part of the notochord has extended into the basisphenoid region, and its capsule has connected it, by ligament, to the broad, flat ossifications of expansions of the same capsule, forming the basi-cccipital or basi-sphenoid plate. The vertebra of the trunk in the fully developed full-sized animal present the following stages of ossification. The neurapophyses coalesce at the top to form the arch, from the summit of which was developed a compressed, subquadrate, moderately high spine, with the truncate, or slightly convex, summit, expanded in the fore-and-aft direction, so as to touch the contiguous spines in the back: the spines are distinct in the tail. The sides of the base of the neural arch are thickened and extended outwards into diapophyses, having a convex articular surface for the attachment of the rib; the forepart is slightly produced at each angle into a zygapophysis looking upward and a little forward; the hinder-part was much produced backwards, supporting two-thirds of the neural spine, and each angle developed into a zygapophysis, with a surface of opposite aspects to the anterior one. In the capsule of the notochord three bony plates were developed, one on the ventral surface, and one on each side, at or near the back part of the diapophysis. These bony plates may be termed "cortical parts" of the centrum, in the same sense in which that term is applied to the element which is called “body of the atlas” in Man and Mammalia, and “subvertebral wedge-bone" at the fore-part of the neck in Enaliosauria. As such ventral or inferior cortical elements co-exist with seemingly complete centrums in the Ichthyosaurus, thus affording ground for deeming them essentially distinct from a true centrum, the term "hypapophyses" had been proposed by Professor Owen for such independent inferior ossifications in and from the notochordal capsule, and by this term may be signified the sub-notochordal plates in Archegosaurus, which co-exist with proper "hæmapophyses," in the tail. In the trunk they are flat, sub * Reptilian aus der Steinkohlen Formation in Deutschland. Sechster Band, p. 61. quadrate, oblong bodies, with the angles rounded off; in the tail they bend upwards by the extension of the ossification from the under to the side-parts of the notochordal capsule-sometimes touching the lateral cortical plates. These serve to strengthen the notochord, and support the intervertebral nerve in its outward passage. The ribs are short, almost straight, expanded and flattened at the ends, round and slender at the middle. They are developed throughout the trunk and along part of the tail, co-existing there with the hæmal arches, as in the menopome.* The hæmal arches, which are at first open at their base, become closed by extension of ossification inwards from each produced angle, converting the notch into a foramen. This forms a wide oval, the apex being produced into a long spine; but towards the end of the tail the spine becomes shortened, and the hæmal arch is reduced to a mere flattened ring. The size of the canal for the protection of the caudal blood-vessels indicates the powerful muscular actions of that part; as the produced spines from both neural and hæmal arches bespeak the provision made for muscular attachments, and the vertical development of the caudal swimming organ. All these modifications of the vertebral column demonstrate the aquatic habits of the Archegosaurus; the limbs being in like manner modified as fins, but so small and feeble as to leave the main part of the function of swimming to be performed, as in fishes and perennibranchiate batrachia, by the tail. The skull of the Archegosaurus appears to have retained much of its primary cartilage internally, and ossification to have been chiefly active at the surface; where, as in the combined dermo-neural ossifications of the skull in the sturgeons and salamandroid fishes, e. g., Polypterus, Amia, Lepidosteus, these ossifications have started from centres more numerous than those of the true vertebral system in the skull of Saurian reptiles. The teeth are usually shed alternately. They consist of osteo-dentine, dentine, and cement. The first substance occupies the centre, the last covers the superficies of the tooth, but is introduced into its substance by many concentric folds extending along the basal half. These folds are indicated by fine longitudinal straight stria along that half of the crown. The section of the tooth at that part gives the same structure which is shown by a like section of a tooth of the Lepidosteus oxyurus. The same principle of dental composition is exemplified in the teeth of most of the ganoid fishes of the Carboniferous and Devonian systems, and is carried out to a great and beautiful degree of complication in the old red Dendrodonts. The repetition of the same principle of dental structure in one of the earliest genera of Reptilia, associated with the defect of ossification of the endo-skelton and the excess of ossification in the exa-skeleton of the head, decisively illustrate the true affinities and low position in the Reptilian class of the so-called Archegosauri. For other details of the peculiar and interesting structure of the animals representing the earliest or oldest known order of Reptiles, Professor Owen referred to the article "Palæontology" in the Encyclopædia Britannica." This order is "carboniferous.' Order II. LABYRINTHODONTIA.-Head defended, as in the Ganocephala, by a continuous casque of externally sculptured and unusually hard and polished osseous plates, including the supplementary "postorbital" and supertemporal bones, but leaving a "foramen parietale." Two occipital condyles. Vomer divided and dentigerous. Two nostrils. Vertebral centra, as well as arches, ossified, biconcave. Pleurapophyses of 66 *Principal Forms of the Skeleton, Orr's "Circle of the Sciences," p. 187, fig. 11. Wyman, "American Journal of the Natural Sciences," October, 1843. |
