Researches on the Structure, Organization, and Classification of the Fossil Reptilia VII Further Observations on Pareiasaurus . an in this respect, since they retain the primitive mode ofunion of the vertebral column with the skull, by means of the basi-occipital boneonly, to which Ichthyosaurus offers a nearer parallel than is found in Pareiasaurus.[It is exceptional for the skull to unite with the vertebral column by thebasi-occipital bone only, but two condyles like those of Mastodonsaurus orActinodon, formed by the basi-occipital bone, are in better osteological harmonywith the structure o
Researches on the Structure, Organization, and Classification of the Fossil Reptilia VII Further Observations on Pareiasaurus . an in this respect, since they retain the primitive mode ofunion of the vertebral column with the skull, by means of the basi-occipital boneonly, to which Ichthyosaurus offers a nearer parallel than is found in Pareiasaurus.[It is exceptional for the skull to unite with the vertebral column by thebasi-occipital bone only, but two condyles like those of Mastodonsaurus orActinodon, formed by the basi-occipital bone, are in better osteological harmonywith the structure of Reptiles, than would be two condyles formed by the 320 PROFESSOR H. G. SEELEY ON THE STRUCTURE, ORGANIZATION, ex-occipital bones, under circumstances in which the basi-occipital element wasnot ossified. I can see no reason to doubt that the basi-occipital element is ossifiedin the Labyrinthodontia; or that it gives attachment to the ex-occipital bones inMastodonsanrus, and Trematosaurus in the way shown in the preceding figure ofthe former, and by Dr. E. Fraass figure of the latter genus, which is herereproduced. Fig. 4. 25as<lafc. Occipital aspect of the skull of Trematosaurus (after E. Fraas) showing the two condyles (G.) formedby the basi-occipital bone and the ex-occipital bones placed vertically (Ux. 0.) upon it. The Labyrinthodontia considered as true Reptilia illuminate the affinities of manyfossil groups of animals in a way which was not obvious so long as they were regardedas formed upon a distinct plan from the reptilian stock.—12th July, 1892.] Vertebral Column of P. bombidens. The vertebral column figured, Phil. B,1888, Plate 12, did not show theventral surfaces of the dorsal vertebrae, while the lateral surfaces which gave attachmentto the ribs, were more or less obscured by matrix; so that the parapophysis anddiapophysis which appear in the dorsal vertebrae, figs. 1 and 2, Plate 18, as separated,as shown in this Tamboer specimen, are connected by bo
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Keywords: ., bookauthorseeleyh, bookcentury1800, bookdecade1890, bookyear1892
