Page:Quarterly Journal of the Geological Society of London, vol. 29.djvu/613

1873.] ; from that of Scelidosaurus Harrisoni it differs in the smaller expansion of its dorsal end ; and from that of Hylæosaurus in the absence of the stout acromial ridge which marks the bladebone of this reptile; whilst to the stupendous scapula of Ceteosaurus oxoniensis my immature bone has a general likeness.

The Coracoid (fig. 2, c) is a thin, flat, subsemicircular bone. It touches the scapula, but it has slipped a little backwards from it. Its scapular border is straight. The glenoid border is the stoutest part of the bone. Between it and the longer straight scapular border is a small notch, and between the posterior glenoid lip and the sternal margin is a large deep incurve. The sternal margin is thin, and its outline is an arc. In an older individual, the bones of which were harder and the matrix better adapted to preserve them, this arc in curve and in length agreed with the corresponding border of an adjacent sternum. The coracoid of this individual was also pierced by a foramen near the union of the glenoid and scapular borders, of which only a trace is discernible in my squeezed immature bone.

Sternum.—A thin shield-like bone, pressed quite flat, lying close to the coracoid, was probably the sternum. It broke to bits with the block of clay in which it was imbedded, during my efforts to extract it from the cliff. The same bone, or rather its anterior moiety, in another individual, here also associated with the coracoid, had a semirhomboidal form. The front or intercoracoid angle was truncated and emarginate; I roughly judged its length to nearly equal one third of the width of the coracoid, measured between the sternal and glenoid borders. The coracoid margin of this sternum agreed in the form and extent of the curve with that of a near-lying coracoid. Mesially, the lateral halves of this sternum included a large angle, the ventral surface of which was smooth and keelless.

Humerus (fig. 2, d).—The left arm-bone lies parallel with the front border of the bladebone, and partly hidden by it. Its length, 3⋅4 inches nearly, equals that of the bladebone. The proximal end bears a subhemispherical articular head (e), placed nearly in the middle, and prolonged upon the dorsal or anconal aspect of the bone. A large crest marks the radial border of the shaft near the proximal end. The shaft itself is somewhat twisted. The ventral surface of the distal end is hidden.

Forearm.—The greatest part of both bones of the forearm could not be preserved. The ulna, for its size, has, I think, as large an olecranon as that represented in Prof. Owen's plate of this bone in Iguanodon, issued by the Palæontographical Society last year. The radius is much broader at the wrist than the ulna, and it forms the principal support of the manus. The radius of a mature individual I found to be 4⋅87 inches long, the ulna slightly more; and the humerus was 5⋅75 inches in length.

Manus (fig. 3).—The bones of the fore foot, together with the distal ends of the radius and ulna much crushed, were lying disconnected and confusedly in the clay, near the larger mass containing the shoulder-blade and coracoid. Two carpals are discernible, one of