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Show 1905.] DINOSAUR CETIOSAURUS LEEDSI. 237 continuous series of 27 vertebrae, of which only some of the foremost are defective in preservation. The first of these middle caudals is the most imperfect, and its neural spine is hypothetically fixed; but the centrum is shown to be sharply rounded below, with a distinctly double facette for the chevron behind. All these vertebrae are much more elongated than the anterior caudals, and somewhat laterally compressed; but they are still slightly constricted, without any lateral pits, while both their articular ends are a little concave. As they are traced backwards, the centra not only decrease in sizs but soon lose the last remnant of a transverse process ; while their neural spines become shorter, Text-fig. 42. Cetiosaurus leedsi.- Anterior caudal vertebra; posterior and (A) right lateral aspects, pz., postzygapophysis; tr., transverse process; zs., zygosphene. [Brit. Mus. no. R. 1984.] About f nat. size. broader, and thinner, and more sharply inclined towards imbrication. The seventh vertebra of this series (text-fig. 43) is especially well preserved. The anterior face of its centrum (text-fig. 43 A ) is relatively broader than its posterior face (text-fig. 43 B), and the transverse process is a mere ovate tubercle (tr.) on the middle of the upper part of its side. The neural spine scarcely overhangs the centrum behind, and its truncated upper end is still slightly hollowed. The prezygapophyses (az.) are large and clasping, but the postzygapophyses (pz.) are feeble, and there is no zygosphene-articulation. A large opening is left for the exit of the spinal |