It is well known that in man the biceps is inserted into the tuberosity of the radius by means of a flattened round tendon. This tendon, however, opposite the bend of the elbow, gives off a broad expansion, which passes into the fascia of the forearm, and is termed _Aponeurosis bicipitis_. In the gorilla this aponeurosis is carried on as strong fibrous bundles of the fascia of the forearm into the palmar fascia. In the gibbon the short head of the muscle does not always start from the lesser tuberosity of the humerus, nor from the tendon of the pectoralis major (Huxley), but sometimes from the edge of the lesser tuberosity, which is here connected with the _latissimus dorsi_, as well as with the sub-scapularis, the brachialis anticus, which is more to the side, and with the triceps. In the gibbon, as Bischoff justly observes, the supinator longus only reaches as far as the centre of the radius, instead of extending to the styloid process of that bone, as it does in other anthropoids, and in man. The palmaris longus is wanting in the gorilla, but not in other anthropoids. The long flexor muscles of the fingers and the lumbricales resemble those of man (Figs. 51, 52). The flexor longus pollicis is absent in the gorilla. Duvernoy considers that it is replaced by a tendon of the long flexor of the fore-finger, but I have been unable to verify the existence of this tendon. The same muscle is also absent in the chimpanzee and the orang, but it may be traced in _Hylobates albimanus_. Chapman states that in the gorilla the pronator radii teres only sends forth one head,[71] but I have found it to be bicipital in animals of this species. The lower or hinder head issues, as in man, from the coronoid process of the ulna. Both in the gorilla and in the chimpanzee it extends far in a downwards direction on the radius (Fig. 52). The flexor carpi radialis starts in the chimpanzee with one head from the inner condyle of the humerus, and with the other from the radius. Bischoff describes the structure of the long abductor of the thumb in the orang, the baboon, the _pithecia_, and the _hapale_ as resembling that of man. But in the gorilla, the chimpanzee, and the macaca the tendon divides into two parts. Nor does one tendon belong, as in man, to a short extensor of the thumb, but the latter is wholly absent, and the division of the tendon only implies a continued division of the attachment to the trapezium, as well as to the metacarpal bones of the thumb. This division of the tendon also occurs in the gorilla, which likewise possesses a short extensor of the thumb. In this point, again, apes display a greater likeness to one another than to man. [Illustration: