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Show 1894.] ANATOMY OF ATHERURA AFRICANA. 689 The median nerve rises from the 6th, 7th, and 8th C. and 1st D. In. the lower third of the arm it gives off a large branch to supply the outer side of the forearm as far as the dorsum of the hand. Just below this twigs are given off to the brachialis anticus, after which the nerve enters the forearm and supplies all the flexor muscles except the flexor carpi ulnaris, but there is no definite anterior interosseous nerve. In the hand the median supplies the thumb-muscles and the skin of the palmar surface of all the fingers. The musculo-spiral derives fibres from all the roots forming the brachial plexus ; it winds round the back of the humerus, supplying the triceps, dorso-epitrochlearis, and skin of the upper arm, but I was unable to find any branch going into the brachialis anticus. Just above the elbow it divides into radial and posterior interosseous; the former runs through the substance of the extensor carpi radialis longior, supplying it and the brevior, after which it is continued down to the back of the hand to supply the skin of the dorsum of the radial three and a half fingers. The posterior interosseous passes deep to the supinator brevis and breaks up into a brush of nerves for the extensor muscles. The ulnar nerve rises from the 8th C. and 1st D. and runs down behind the internal condyle, supplying the epitrochleo-anconeus, flexor carpi ulnaris, and palmaris brevis, but not the flexor profundus digitorum. In the hand it supplies all the deep muscles of the palm but no skin. Before it reaches the wrist a dorsal cutaneous branch is given off, which supplies the skin of the back of the ulnar one and a half fingers. The internal cutaneous nerves come from the IstD. and supply the skin of the inner side of the arm and forearm. The anterior thoracic nerve rises from the 8th C. and 1st D., and is one of the largest nerves in the plexus; it supplies the pectoral muscles and the ventro-lateral part of the panniculus. The posterior thoracic nerve comes from the 7th C. and runs back behind the plexus to supply the serratus magnus. I a m not certain of the origins of the nerves to the teres major and latissimus dorsi. The former does not supply any of the sub-scapularis. The lumbar plexus is formed by the 2nd, 3rd, and 4th lumbar nerves. The first lumbar is quite separate and runs round the body-walls after the manner of the intercostal nerves ; it divides into two branches, which probably correspond to the ilio-hypo-gastric and ilio-inguinal nerves of human anatomy. The genito-crural nerve rises from the 2nd L. and appears on the surface of the psoas magnus, after which it crosses the tendon of the psoas parvus from within outwards ; it then runs back to supply the skin over the region of the groin. I failed to notice any branches going to the muscular wall of the inguinal pouch. The external cutaneous nerve comes from the 2nd and 3rd L. and appears on the surface of the psoas magnus external to the P R O C . Z O O L . Soc-1894, N o . X L V I . 46 |