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Show 1869.] MYOLOGY OF MENOBRANCHUS LATERALIS. 461 sertion of the subclavius, and is inserted into the upper part of the radius. Triceps (figs. 3 & 6, T). A large muscle arising from the postero-external angle of the coracoid from the outer and inner sides of the shaft of the humerus, and, by direct continuation, from the latissimus dorsi. It is inserted into the proximal part of the ulna. Fig. 7. Deeper muscles of extensor surface of right forearm, the extensor longus being cut and reflected. E. B. Extensor brevis. E. L. Extensor longus. P. Q. Pronator quadratus. 8. LA & S. L. 2. Supinator longus. JJ. Ulnaris. The supinator longus (figs. 3, 4, 6, & 7, S. L) appears to be double (S.L. 1, and S.L. 2, figs. 3 & 7). unless the more internal part (S. L. 2) represents an extensor radialis. lt arises from about the lower third of the humerus, and is inserted into the lower part of the outer (or radial) side of the radius. Ulnaris (figs. 3 & 7, U). This is a rather bulky muscle passing from the distal part of the ulnar side of the humerus downwards to the corresponding side of the carpus. The pronator teres (figs. 4 & 6, P. T) also appears to be double (P. T. 1 and P. T. 2, fig. 6). Both parts extend from the lower end of the inner (or ulnar) border of the humerus, and extend downwards and outwards to the lower part of the radius. Extensor longus (figs. 3 & 7, E. Ii). This muscle extends from the outer (or radial) border of the lower part of the humerus, and, expanding as it passes downwards, is inserted into the digits. Extensor brevis (figs. 3 & 7, E. B). This is a very small muscle which arises from the radial side of the distal end of the ulna, and, passing obliquely downwards and outwards, goes mainly, if not exclusively, to the most radial digit. Pronator quadratus (?) (fig. 7, P.Q). A small muscle passing from the ulna to the radius, obliquely downwards, and situated between the ulnaris, the inner part of the supinator longus, and the extensor brevis. Flexor longus (figs. 4 & 6, F. L). This muscle arises from the ulnar side of the lower end of the humerus, and, expanding as it passes downwards, is implanted into the digits. Flexor brevis (fig. 6, F. B). A small subtriangular muscle which |