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Show 1905. J ANATOMY OF THE LEATHERY TURTLE. 301 Origin : from the ventral surface of the outer third of the coracoid. Insertion: upon the humerus in the hollow between the lateral and median processes, just proximal to the insertion of the pectoralis. A thin sheet of muscle capping the shoulder. The median nerve follows its hinder border, lying between it and the coraco-brachialis brevis internus. Coraco-brachialis brevis internus (text-figs. 58, 60, 61, & 64. 46).-Origin : from the outer three-fourths of the hinder border of the coracoid, encroaching somewhat upon both dorsal and ventral surfaces. Insertion : upon the processus medialis of the humerus. An undetermined muscle (text-figs. 60 & 62. 46 a), probably a separate part of the coraco-brachialis brevis internus. Origin : from the ventral and posterior border of the coracoid, extending slightly on to the coraco-scapular ligament. Insertion : upon the extensor surface of the median process of the humerus between the insertions of the coraco-brachialis brevis internus and of the subscapularis. Coraco-antebrachialis (biceps) (text-figs. 58, 61, & 64. 47).- Origin: from the median end of the ventral surface of the coracoid, posterior to the origin of the supra-coracoideus. Insertion : by a round tendon to the heads of the radius and ulna. This muscle passes into the arm between the head of the humerus and the median process, overlying the median nerve. As it enters the arm it forms a single rounded tendon that extends to the hollow of the elbow. Here, the tendon unites to a great extent with the dense connective tissue upon the surface of the humero-radialis longus dorsalis, but strands can be traced to both the ulna and radius. Fiirbringer describes a separation of the muscle into definite superficial and deep parts during its passage along the humerus. Humero-antebrachialis inferior (text-fig. 64. 48).-Origin : from the flexor surface of the humerus distal to the lateral process. Insertion: by tendon upon the flexor surface of the head of the ulna, in common with the tendon of the biceps. Testo-humeralis dorsi (latissimus dorsi) (text-figs. 55 & 62, 49).-Origin : from the carapace along the anterior border of the second rib just in front of the testo-coracoideus, and along the outer margin of the scapular fossette to the posterior limit of the nuchal plate. Insertion : upon the middle of the extensor surface of the humerus between the insertion of the subscapularis and the origin of the a n c o n f e u s . Fiirbringer states that in Chelone (adults) the origin of this muscle extends back to the third rib, but that this is a backward migration that takes place after embryonic lif§. Scapulo-claviculo-plastro-humeralis (Deltoideus) (text-figs. 58, 59, & 62. 50). - This consists of two entirely independent muscles:- a. Pars clavicido-plastro-humeralis.-Origin: from a median ventral raphe in front of the shoulder-girdle and from the anterior |