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THE SHOULDER

    The Shoulder consists of two bones, the scapula and clavicle.

    THE SCAPULA,     e.     This large flat bone situated at the median region of the chest has an upper articular portion, a rounded neck, and an anterior and a posterior wide surface. The superior articular portion of the scapula is rounded behind and is joined by synchondrosis to the internal part of the head of the clavicle, from this articular portion the bone proceeds upwards and behind, forming the large curve which distinguishes the superior part of the posterior surface of this bone. In the same manner a curve is produced anteriorly but of a much less extensive sweep. The outer aspect of the scapula is marked in the centre by a considerable uprising, in consequence of which it is rendered irregularly convex and in some places concave and flat.
    Connexion.    In the middle with one another, before with the sternum and clavicles, behind with the anterior ventral rib, and superiorly with the clavicle and humerus.
    We figure in the twenty-sixth plate the scapula of the large individual found at Marsh's Elm, which differs in shape from that of the Triatarsostinus.

    THE CLAVICLE,     f.    The clavicle is a long bone with a thickened articular end posteriorly, a body and a widened and thin anterior portion. Its thickened articular end is flattened without and within and has above a rounded side and below a concave one. The anterior widened portion is curved above and slightly grooved; it supports the two lateral articulatory surfaces of the sternum.
    Connexion.    Before with the sternum and anterior flattened surfaces of the scapula and behind to the articular extremity of the scapula, thus completing the glenoid cavity for the humcrus.
    The clavicles found in plate twenty-five totally differ from those of the Triatarsostinus in shape.

    OF THE ARM. g. The humerus is long, curved and strong. It has a head, a body and an inferior extremity. The head of the humerus is large, round and deeply marked with many fossæ and eminences. Around this irregular surface the bone presents a roughened ridge for the capsular ligament. The body is flattened and convex from side to side and upon its upper-third is a tubercle for the attachment of muscles. It is concave and thin behind, before rounded and convex throughout its long diameter. The inferior extremity is wider and flatter than any other part and is divided into an anterior and a posterior portion by a depression in its centre, which stretches forth in a sharp point between the radius and ulna.
    Connexion.   Anteriorly and above with the scapula and clavicle; inferiorly with the radius and ulna.

    OF THE FORE-ARM.     The radius (h) has an upper and an under flattened surface, a superior and an inferior articular extremity, an external convex and rounded boundary and an anterior and internal semi-lunar edge.
    Connexion. Above with the humerus and below with the external and middle bone of the carpus.
    The ulna (i) has a semi-lunar edge posteriorly like the radius but it is not so much curved, it is a rounded bone with its greatest diameter from above to below, and has an anterior convex border and an upper and under articular surface.
    Connexion.    Above to the humerus and below by cartilage to the pisiform bone.

THE ANTERIOR PADDLE.

    THE CARPUS.     Two longitudinal rows each containing three bones form the carpus. We call them, as in the Ichthyosaurus, scaphoid, cuneiform and pisiform above; trapezium, trapezoid and unciform below.
    The scaphoid bone is nearly circular; its upper and under surfaces are Hat and smooth and its edges plain. It is in close juxta-position with the outer edge of the cuneiform bone and its inferior portion articulates with the trapezium.
    The cuneiform bone by chance justifies the name we give it and has, like all the bones of the carpus, a flat upper and under surface and plain edges. Its wedge-like portion is insinuated between the radius and ulna; it articulates with the scaphoid without, below with the trapezium and within to the pisiform bone.
    The pisiformis is smaller than the two just described and has its long axis from side to side. It articulates with the ulna above, below to the unciform bone and within to the trapezoid.
    The trapezium, the first bone of the digital row, is a round, circular bone, having upon its superior portion an articular junction with the scaphoid and cuneiform bones.