90 THE EXTINCT BAT R ACII I A, REPTI LI A Length ft. Polyacantims, Owen, 9 Scelidosaurus harrisonii, Oven, 12 Iguanodon anglicus, Meyer, llylaeosanrus armatus, Mant, liadrosaurus foulkei, Leidy, 28 91 28 Poecilopleurum bucklandii, Deslong, 25* Megalosaurus bucklandii, Mant, ?30* Laelaps aquilunguis, Cope, 24 Teratosaurus suevicus, Meyer, ? 30 Ornithotarsus inimanis, Cope, ? 35 Prof. Owen suspects the animals of this order to have had the septum of the ventricles of the heart complete as in the Crococlilia. It is an interesting inquiry whether there were two aorta-roots or only one, and if one, whether the right or left remained. I have little doubt that the Dinosauria further resembled Crococlilia in having the lateral lobes of the eerebelhun developed, and the vermis plicate. The affinity to the modern Sauna, or Lacertilia, winch some authors have allowed of, is very slight ; the Crococlilia, though somewhat removed, are the nearest living allies. If we consent to a derivative relation between types, we must consider this order to have given origin by divergence and metamorphosis to both the ?Vfanimalia and Ayes. The structure and embryology of the last two classes forbid the idea that either could have been derived from the other. Besides the differences in the structure of' the tarsus and metatarsus observed in this order, there are marked differences in that of the tibia. Thus most of the order present a very prominent spine and crest, of bird-like character ; but Plateosaurus Meyer and Tera-tosaurus 'Meyer both Triassic genera, appear to possess this character in a very slight degree, the former scarcely at all. I have, therefore, not included them in the groups following. ORTHOPODA. Cope Piece. Acad. Phila., 1866, 317. The.rosateria Haeckel, 1863. Proximal tarsal bones distinct from each other and from the tibia, articulating with a tibia and with a terminal face of a well developed fibula. The ilium with a massive narrowed anterior prolongation. In the few genera of this suborder, of which the teeth have been discovered, a successive divergence from the type of the Goniopocla is visible, in the shortening and increase in
- These estimates I have reason to think exaggerated.
