T he recognition of what are now commonly termed the Dinosauria , as a peculiar group of the Reptilia , is due to that remarkable man whose recent death all who are interested in the progress of sound palæeontology must deplore–Hermann von Meyer. In his ‘Palælogiea,’ published so long ago as 1832 ∗, Von Meyer classifies fossil reptiles according to the nature of their locomotive organs; and his second division, defined as “ Saurians, with limbs like those of the heavy terrestrial Mammalia,” is established for Megalosaurus and Iguanodon . To this group Von Meyer subsequently applied the name of Pachypodes or Pachypoda . Nine years afterwards Professor Owen, in his “Report on British Fossil Reptilia,” conferred a new name upon the group, and attempted to give it a closer definition, in the following passages :– “ Dinosaurians .–This group, which includes at least three well established genera of Saurians, is characterized by a large sacrum composed of five ankylosed vertebræ of unusual construction, by the height and breadth and outward sculpturing of the neural arches of the dorsal vertebræ, by the twofold articulation of the ribs to the vertebræ, viz. at the anterior part of the spine by a head and tuberele, and along the rest of the trunk by a tuberele attached to the transverse process only; by broad and sometimes complicated coracoids and long and slender clavicles, whereby Croeodilian characters of the vertebral column are combined with a Lacertian type of the pectoral arch ; the dental organs also exhibit the same transitional