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Show 1905.] DINOSAUR CETIOSAURUS LEEDSI. 241 in the fossil at the upper border. The bone becomes thick and massive in the lower part of the proximal end, where it forms half the articular socket for the humerus ; above this it expands into a thin lamina of unknown but probably small extent. The coracoid seems to have been nearly quadrangular and somewhat broader than long, though its upper edge is incomplete in the fossil. Its thin upper half is anchylosed with the proximal expansion of the scapula; but its massive lower half, which enters into the articular socket for the humerus, is separated from the scapula by a cleft, which must have been originally filled with cartilage. The bone is pierced with the usual oblique oval foramen near the middle of the border which articulates with the scapula. The humerus (text-fig. 47, p. 240) is complete in the fossil and scarcely crushed; but an opportune transverse fracture permits the observation that the shaft has a small cavity, perhaps an original medullary cavity, perhaps due to decay (text-fig. 47 A). As seen from the front, the bone is short and stout, with the thickened articular head near the inner end of its expanded proximal border. The deltoid crest (cl.) is thick and prominent, not extending below the upper half of the shaft. The distal end of the bone is deeply furrowed for a cap of cartilage, and its large inner condyle bulges downwards. The ulna and radius (text-fig. 48, u., r., p. 240) are imperfect and much broken distally ; but there is not much doubt about the accuracy of their length stated in the table on p. 243, and the shape of their upper articular end is clearly as shown in text-fig. 48. The manus is unknown. Hind Limb. As shown by the table of measurements on p. 243, the hind limb is considerably longer than the fore limb, the ratio being about 3 to 2. The ilium is fragmentary on both sides of the fossil, but the one bone fortunately supplements the other, and justifies the complete outline given in text-fig. 39, p. 233. This element is noteworthy for its great antero-posterior extent and the length of the slender pedicle which supports the pubis. The upper rim of the large perforated acetabulum is not very prominent. The pubis and ischium of another specimen (Brit. Mus. no. R. 1988) have already been described by Prof. Seeley, and have been added in outline to text-fig. 39. The femur (text-fig. 49, p. 242) is complete from end to end, but part of the surface of the shaft has decayed and been restored with plaster. It is a remarkably slender bone for so massive an animal, and in broken sections there is no trace of a small medullary cavity. The head of the bone (h.) is relatively large and curved inwards, and it rises above the level of the great trochanter (y.t.). The shaft is antero-posteriorly compressed, but bulges considerably backwards just above its lower half into a prominent fourth trochanter (t.) on the inner border. The distal condyles are about equal and well separated by a groove. The tibia and fibula are too fragmentary for description, and the 16- |